Exam 3: Questions
Know how northern and southern species were differentially affected by the filter during the GABI.
1.because northern species were better migrators 2.northern species were better at surviving and speciating 3. northern species were superior competitors
Know the general ways that biota responded to changes in their habitat distribution during the Pleistocene.
1.follow optimal habitat as it shifts positions-plants and trees moved slower than animals, but they tend to be more adaptable than animals do. 2.remain in place and adapt to new conditions 3. Lose habitat area, reduce range, which leads to extinctions. Generally biomes shifted from 10 degrees to 20 degrees in latitude between glacial maxima and interglacials. Biomes generally maintained their relative positions. Species tended to respond independently thereby disrupting long-established communities
Be able to rank species turnover rates based on distances to colonist sources and island areas (e.g., small & far vs large and near islands).
1.large near 2.large far 3. Small, near 4.small, far; TSN > TSF ≈ TLN > TLF
Be able to rank equilibrium species numbers based on distances to colonist sources and island areas (e.g., small & far vs large and near islands).
1.large, near island 2.large, far islands 3.small, near islands 4. Small, far islands; SSF < SSN ≈ SLF < SLN
Outline how an equilibrium number of species and turnover rate can be determined using ETIB.
A small, far island will have a lower number of species at equilibrium than a small near island. Therefore the turnover for a small, near island is much greater than turnover for a small far island. However, a large, far island will have a smaller number of species at equilibrium than a large, near island. Therefore, turnover for a large near island will be greater than turnover for a large far island.
Understand the roles of corridors and nunataks in the distribution of North American biota during and after the last glacial maximum.
As ice formed and melted you get a refugia. It is though that there was a refugium where cordilleran and Laurentide ice sheets met. This allowed species to skip down on these areas and move down, as well as live there. Nunataks are where small tips are refugium between inland ice sheets. Route through Beringia through the ice-free corridor and down to the southern refugium. For example, with the boloria species, which are butterflies. They lived in colder areas, so as the climate warmed, they moved up and up in elevation, but eventually they are only at the tips of mountains.
Outline how communities and biomes responded to climate change in the Pleistocene.
As ice formed biomes shifted further south in the Northern hemisphere. As ice receded biomes shifted north again in the Norther Hemisphere. Note that while the zones tended to shift in concert, the upper zones became narrower as they shifted to higher elevations in response to global warming. Some biomes/communities disappeared entirely because their range was so narrow and they could not compete with other biomes/species. Rather than responding as integrated units to shifts in climates, communities often disintegrate with species responding as an individualistic manner to produce non-analogue assemblages(communities for which there is no modern equivalent). These individualistic response to climate change resulted from both novelty in climatic regimes and interspecific differences in niches and dispersal capacities. Climate-induced range shifts differed markedly within as well as among species, depending on the particular regions inhabited by a species' populations. Although the coverage of low land forests has remained roughly unchanged, Andean forests have expanded, while paramo habitats and areas of perennial snow and grassparamo become elevationally compressed.
Know the general trend in endemicity that is found on islands and be able to outline a general explanation for it.
As immigration decreases, evolution of new taxa becomes primary means of increasing S(number of species of at equilibrium). Gene flow and extinctions work against these processes. On the very large, remote islands and archipelagoes, the distinctiveness of insular biotas may be further amplified over time, sometimes to extreme levels, by in situ(within-island or within-archipelago) speciation. The result is that such islands and archipelagoes often become hotspots of endemicity. More remote islands should experience less frequent immigration and therefore lower gene flow from mainland populations, which would otherwise swamp any incipient diversification well before insular populations could diverge to form a new species. Endemicity is highest for poorly dispersing taxa.
Be able to use the Champlain Sea, Beringia, Australasia examples to explain the importance of sea level change.
Champlain sea: When sea levels rose, more species were able to use this avenue to migrate further inland near the Great lakes region today. The spilled over into areas that they were not previously covering. Once the sea levels decreased the species that migrated inland stayed in their new locations. Glaciation during the Pleistocene resulted in the lowering of sea levels by 100-135 m below their current levels, although changes were both asynchronous and of differing magnitude. Beringia formed because of glaciation. Organisms were able to cross from Alaska to Asia via a land bridge. But when glaciers melted and sea levels rose they were separated.
Outline how the distribution of habitat changed as a result of glacial/interglacial cycles.
Changes in prime habitat including location, extent, and configuration(continuous or patchy); climatic changes in the environmental zones. Changes in the connectivity of prime habitat, loss or gain of dispersal corridors. Species had to evolve independently each other in certain areas because of glacier movement and melting/freezing.
Examples of Autochthonous endemism
Dakota Skipper
Be able to explain why Dakota skipper is considered endemic.
Dakota skipper is endemic because it is only found in the Great Plains range. So it is in a particular scale, at a hierarchal level, and is nested within other similar species of its taxon
Outline the types of data that are used to infer glacial history.
Eccentricity, insolation, and ice volume, obliquity
Outline how evolutionary convergence can occur and be able to provide examples.
Evolutionary convergence is the process by which taxonomically unrelated species in geographically isolated regions have evolved similar forms and/or similar ecological roles under the influence of similar selective pressures. Similar ecological pressures in two or more isolated locations can lead to striking similarities in ecological traits. conservatism is a tendency of species to maintain ancestral traits in isolation . Phylogenetic traits is like with mammals and birds that are quadrupedal or internal skeletons, they are due to traits that we inherit from different ancestors. Drawing the same body form can arise in plaggic marine organisms because they're fast pursuit organisms and they converge on these traits. This can occur with client convergent in Mediterranean clients like in the Mediterranean, on the western coast of North America and South America, the southern tip of Africa, and in the southern portion of Australia. This occurred with desert rodents and 1 extinct marsupial these species were originally found on several different places throughout gondwana and are now found throughout the world in North America, South America, Eurasia, Australia, and Africa. There also several examples of convergence between North America and Australia. For the Wolf in North America there is a Tasmanian Wolf in Australia. For the ocelot in North America others a native cat in Australia. There are several other examples of this like the Groundhog in North America and the wombat in Australia.
Know what aspects of island biogeography are accounted for in the general Dynamic Model and other newer models that are not accounted for in the ETIB.
Fundamental processes like immigration, extinction, speciation are spatially and temporally scale depend. Processes that interact and covary like immigration decreasing and speciation increasing with island isolation. Biological capacities of species to colonize covary like metabolism and ability to raft. Ecological interactions will drive feedbacks. Islands and island systems have their own ontogenies and geologic histories that influence their biota like volcanism. The difference is that time is an independent variable here, and is important in the dynamics in island biotas. Species richness is a dependent variable. Carrying capacity here is only 'biotic' factors and is the maximum number of species that can be supported.
Know the general pattern of mammal movement as the glaciers receded.
Geographic range shifts in these species often exceeded 1,000 km, varying substantially in direction and often being displaced in directions that run counter to simplistic expectations of response to glacial advance and recession. Although these range shifts were broadly individualistic, they were far from random, with species often shifting in similar directions-reflecting either an ecological interdependence among species or species of similar environmental and climatic tolerances shifting their ranges along the same environmental gradients or being impeded by the same geographic barriers.
Examples of Taxonomic relict endemism
Ginko(only 1 species of tree left), Coelocanth(lobe finned fish, two species known, used to be only known through fossil record), Cui-ui (lake sucker in a small family of fish)
Have a basic knowledge of the timing and geography of North American glaciers during the last glacial maximum.
Ice sheet in a the northern hemisphere extended from the Arctic southward to cover most of North America and Central Asia to approximately 45 degrees North latitude. Ice sheets as much as 3 km deep and extending far into temperate latitudes and to even lower latitudes across the mountainous regions of NA, Europe, and Asia. The two main ice sheets in NA were the Laurentide Ice sheet(east coast through to the Rockies in NA) and Cordilleran ice sheet(west coast of NA).
Have a general idea of how glaciers were distributed worldwide during the last maximum.
Ice sheets as much as 3 km deep and extending far into temperate latitudes and to even lower latitudes across the mountainous regions of NA, Europe, and Asia. The southern hemisphere has much less landmass in temperature and sub Arctic regions, and glaciation was not extensive. Glaciation was mostly confined to high elevations at high southern latitudes like in the central plateau of Tasmania in the southern Alps of New Zealand. The Andean cordillera was glaciated, but the greatest ice coverage was in Chile and Argentina. Mainland Australia was on glaciated except for the Victorian Alps and Africa lacked glaciation except in the Atlas mountains of the extreme northwest corner and in the highest mountains of eastern Africa.
Outline the conceptual model of the drivers of the patterns seen with the island rule.
Immigrant selection for larger individuals and ecological release from larger species for smaller species like rodents on the mainland. Smaller animals also have fewer competitors, few (or no) predators, and fewer pathogens on islands, which allows smaller species to get bigger. For larger animals, there are resource limitations on islands. As well as ecological release from predators and small competitors, which allows larger animals to be smaller. Thought that a lot of larger animals got to their size because being protected from predators, so on islands they can be smaller without worrying about being eaten. There are also dominant species on islands that are different than those on the mainland. This affects dispersal ability and colonizing ability (ability to survive and reproduce on islands). Cope's rule leads to ecological character displacement in three species. Then Island rule comes into place where ecological character release occurs. Eventually resulting evolutionary transformations in disharmonic assemblages or insular anomalies or species going extinct on islands
Be able to explain how immigration rates change with distance to species source in ETIB.
Immigration rates are higher when an island is near the mainland/species source compare to an island that is far.
Give some examples of loss of dispersal ability for some island species.
In birds flightlessness: kiwis, moas, ducks and geese, owls, parrots, cormorants, Kakapo. Kakapo is called an owl parrot. It is a species of large flightless, nocturnal, ground-dwelling parrot endemic to New Zealand. Most of the birds have vestigial wings and don't use their wings to move. Invertebrates that are flightlessness on islands. Giant Weta are one of these species. Endemic to islands around New Zealand. Basically, a giant cricket that can get up to 70 grams. Heaviest insect known.
Outline in general how Milankovitch cycles cause glacial/interglacial episodes.
Milankovitch cycles are changes in the characteristics of earth's orbit around the sun and have been among the key drivers of global climate change in the Phanerozoic eon, especially during the Pleistocene epochs, when approximately 65% of the earth's land surface had drifted to the northern hemisphere. The key drivers of glacial and interglacial cycles have been astronomical, they have resulted from cyclical changes in earth orbit about the sun, which in turn oven driven by changes in the position of the planets and their magnetic pull on earth. The repeated but comparatively brief events of global warming during the Pleistocene correspond with periods in the summer solstice in the northern hemisphere occur when earth was closest to the sun (perihelion). this orbital configuration also contributed to relatively cold winters (are you winter solstice in the northern hemisphere occurred when earth was farthest from the sun). the cold temperatures reduced evaporative infusion of moisture into the atmosphere, thus reducing snowfall. The overall result in the northern hemisphere was that snow and ice not during summers far exceeding accumulation during winters, thus triggering the onset of an interglacial periods. Explanations for the dramatic swings between glacial and interglacial conditions also include feedback effects (IE reduced albedo's ice sheets weighing; Increased production of CO2 is plant productivity increases and their impact on the earth). Winter snowfall was exceeded by summer snowmelt, marking the onset of an interglacial such as the one that began about 11.7 BP and continues today. Eventually the Milankovitch cycles that characterize earth's orbit will combine to reverse these conditions and another glacial period will begin
Know some examples of island endemics.
Moas are endemic to the New Zealand, all of which are dead now. New Guinea contains many endemic species. Rodents and Frogs are also highly endemic to islands because it is difficult for them to disperse through a large ocean area. Spiders are also species that are rich in endemism.
Know some examples disjunction.
Nothofagus obliqua(south American beach tree), found in New Zealand and Australia; species of ratities(flightless birds) found in SA, Africa, Austriali a(and associated Islands); Hines Emerald Dragonfly(somatochlora, found in Wisconsin/Illinois/Minnesota region); Aphitropical plants; Long-finned pilot whale and right whales;
Outline the process of adaptive radiations on islands and be able to provide some examples.
On the islands of Hawaii. There is strong filtering to get to islands; need good colonizers eventually speciation occurs and there is ecological release and niche expansion or species. This occurred with the species Dubautia. It is dispersed throughout all of the islands of Hawaii.
Provide examples of empirically measured species area relationships.
PJ darlington's species area for reptiles and amphibians of the west indies. Richness increases less rapidly for the larger islands. F. Preston's species area curves showed sample effects of area that most species are represented by few individuals, a few species are very common, sampling larger areas increases detection of more species and more individuals/species.
Explain the biological meanings of the terms in the species area relationship equations.
S = cAz or log(S) = log (c) + zlog(A). Where S=Species richness, A=Island Area, C=fitted constant, and z=slope of the line. Species richness indicates how many species are on that island. Island area is just the size of the island. Together they form the z line relationship which indicates the relationship between species richness and island area.
Give some examples of species isolation estimates.
S = k1e-k2(I) . One example is with Moluccan and Melanesian Resident land birds. Degree of saturation is the number of species on New Guinea versus on nay given island. This relationship can be linearized to allow statistical analysis and comparisons among studies. Many studies reports significant species isolation relationships, especially when island isolation varies substantially and when the effects of the island area are statistically 'controlled'. however, even today the species isolation relationship remains less frequently documented than the species area relationship.
Explain how the Isthmus of Panama acted as a dispersal filter during the GABI.
Since its formation, the Central American land bridge has served more as a filter than as a corridor for dispersal. It is suggested that dispersal across the land bridge was strongly influenced by the climatic cycles of the pleistocene. Interchange was greater during glacial periods, when Savannah habitats expanded to cover much of Central America and northern South America and when the lowering of the sea level opened more terrestrial habitat along the corridor. The overall diversity of South America fauna increase because of the invasion, establishment, and subsequent diversification of lineages from North America.
examples of disjunct taxa/species.
South American beach tree found in NZ, Australia, hine's emerald dragonfly, ratities, amphitropical plants, long-finned pilot whale, right whale,
Examples of neoendemic species
Sticklebacks, Catadromous Salmonids (Steelhead Trout, fresh water rainbow trout)
Be able to explain why endemic taxa account for a higher proportion of the biota on large far islands relative to near small islands.
Strong filtering to get to islands which means they are good colonizers. Eventually speciation occurs and there is ecological release and niche expansion.
Outline what we might learn about current global warming by studying Pleistocene glacial/interglacial events.
That while global warming and cooling is normal, what ours now is not normal. The duration of the interglacial predicted by this simulation is uncharacteristically long. The relationship between eccentricity of Earth's orbit, insolation in the Northern hemisphere, and glaciation is evident in the reconstruction of these cyclical changes during the late Pleistocene. We should be starting to cool the earth soon, but we are not due to global warming.
Explain how mountains become ecologically/functionally shorter during transitions from glacial to interglacial periods.
The biome range becomes much shorter and so many species also tend to go extinct because their range does not exist or they were outcompeted.
Be able to explain why ETIB is a "dynamic" model.
The equilibrium model is termed dynamic because immigration and extinction are held to be recurrent, opposing processes, maintaining a relatively stable species number despite ongoing changes in species composition
Outline the island rule and know how it applies to specific cases of island gigantism and dwarfism.
The island rules is that on isolated, species poor islands you expect evolution toward he optimal body size for each "functional group." There is ecological niche expansion, so that species can expand or shrink to their optimal body size. Ecological function is like a predator, herbivore, volant. On the mainland if you're a grazer, you cannot get bigger because there are ones that are bigger than you. On an island you can reach the optimal size because some of those constraints go away. Island gigantism is that smaller forms tend to be bigger on islands. Rodents have a strong trend towards gigantism. Bats trend towards gigantism Island dwarfism larger forms tend to be smaller on islands. Artiodactyla tend to trend towards dwarfism. An island dwarf in the Human Family Homo Floresiensis these were found on the island of Flores in Indonesia. Around 94,000 to 13,000 years ago
Be able to outline the above processes in unglaciated areas like the desert southwest.
Unglaciated areas during the Pleistocene several biomes shifted downward in elevation. Currently though the areas that were previously occupied by Woodlands and some grasslands have shifted upwards and created a more desert arid environment at the bottom of mountains. Clearly shows latitudinal and elevational movement of species and communities.
Explain how extinction rates change with island area in ETIB.
When looking at just extinction rates and island area the extinction rate of a small island is higher than the extinction of a large island
Outline the paradox of loss of dispersal in island species in the context of the "sticking to the wreck" concept.
ancestors have to be really good dispersers, but then descendants are not good dispersers. This is linked to descendants becoming good at being on the island and excelling at that, not trying to disperse to other places because you will most likely not make it. those on most isolated oceanic islands, have little or no ability to disperse to other islands. Essentially individuals that leave the island are very unlikely to make it safely to original source or another island. New Zealand's walking bat is a short-tailed bat, two species were known, but the other is thought to be extinct due to predation by feral cats. The other one is heavily protected.
Explain why areas of endemism are important to conservation efforts.
areas of endemism are important for conservation efforts. It's important so that you can preserve the species without having to worry about them dying off. A good example of this is the Devils hole pupfish that is endemic to one specific Lake in Nevada. A disease would wipe out the entire species of fish because they're only in that specifically in Nevada. However, they have these species also grown in captivity, but without it the species would die off. Additionally it protects other species that have larger endemic zones
Know which phenomena counteract the evolution of island endemics in terms of the taxa themselves and geographic characteristics of islands.
as island become more isolated, the only way the islands can evolve or have new species is through evolution. A higher habitat diversity is linked to a larger area. Additionally, the more isolated an island it is easier for the species to differentiate without gene flow. Larger area islands also help to lower extinction rates. Gene flow and extinctions work against islands that are smaller and closer to the mainland, they work against evolution. An island that is farther away and larger allows the species to evolve and become endemic to that area because migrating after being on the island, would be bad because it would lead to higher species die off most likely. Endemicity is highest for poorly dispersing taxa.
Outline the relationship between pluvial lakes and current sand dunes in the desert southwest.
because glacial periods reduce evaporative input of water into the atmosphere, they are often marked by regional to global aridification and the expansion of deserts and other Xeric ecosystems. Thus, the effect of sand areas is much greater during the last glacial maximum than today. During the last glacial maximum, The temperatures were more cool than it was previously with some areas that are slightly similar today. the precipitation was drier than it is today with some spots that were a lot more dry today, and sometimes cooler spots. Overall there was cooling with decreased evaporation, and decreased precipitation, an increase in aridity and desertification. sand dunes are windblown deposits that were on the land. Monsoons were generally weakest during glacial Maxima , often resulting in aridification of otherwise moist tropical regions. By reducing the evaporative input to the hydrosphere, glacial periods are also characterized by general expansion of desert and other arid ecosystems.
Contrast the concepts of biomes and biogeographic regions.
biomes are defined by soil and climate determining the dominant vegetation type. biogeographic regions recognize that these areas contain endemic and closely related taxa in many different groups.
examples of provincial taxa/species
endemic fishes based on major drainages, mammals and freshwater species between Neartic and Neotropics
Know the general pattern of plant community distribution changes both latitudinally and on mountains.
even in those regions with significant shifts of biomes, plant communities di not simply move as entire, integrated entities up and down the mountains. Rather they changed dramatically in species composition. During the LGM most plant species in NA Grand Canyon occurred lower than they are found today, indicated a much cooler and wetter climate. Many of the species that inhabited areas along the rim of the Grand Canyon are no longer found in similar communities in the same region.
examples of endemic taxa/species
family heteromyidae(desert mice), devil's hole pupfish(cyprinidon diabolis), Dakota skipper in the great plains, islands off the coast of california support several endemic species, Cui ui, monotremes
Be able to explain the types of data used, and the results, of studies of mammalian community structure as the last glaciers receded.
fossil pollen records and fossil records in Beringia. Looking at plateaus that previously formed
Compare the general rates of post
glacial dispersal for plants and mammals.-Shifts in vegetation zones of eastern North America during the most recent deglaciation. There was a great southward expansion of boreal forest and tundra along the Mississippi river valley and Appalachian Mountains. Although there was much variation within taxonomic groups, plants tended to shift more slowly than animals. The geographic dynamics of species during the Pleistocene created many isolated populations, in some cases promoting evolutionary divergence and diversification of lineages.
examples of cosmopolitan taxa/species.
humans, some microbes, peregrine Falcon(falco peregrinus), Senecio spp., Vespertilionid bats
Outline the major climatic changes that occurred in the western hemisphere during the last glacial maximum.
in general, climactic zones shifted towards the equator during glacial periods and poleward during interglacial periods. The largest northern ice sheets are so massive that they greatly reduce the flow of cool polar air masses to non-glaciated regions. Despite generally cooler conditions, glacial winters were less severe, while glacial summers were cooler and less subject to the heat waves that characterize contemporary climates, especially in temperate regions. This pattern of cooler and more equitable climates was true of marine environments as well. Glaciers cause dramatic changes in prevailing winds and ocean currents, which strongly influences regional climates. During the LGM , the jet stream in North America split and diverged around the glaciers an anti cyclonic circulation pattern was established over the Laurentide ice sheet. Along the southwestern edge of the ice sheet, relatively dry easterly winds from the interior cause lakes in the American northwest to dry up. While cold and dry conditions characterized the glacial climates of this and other temperate regions some regions were wetter during the glacial-pluvial periods.
Know, in general, the role of islands as places with high endemism.
island there typically areas of high endemism. New Zealand and Australia are like large islands. On these large islands they have several species that have been able to persist because their predators are not in the area. Additionally there is examples of species that are only found there simply because the other species that would eat them or outcompete them do not live there
Be able to outline hypotheses that explain the megafaunal extinction associated with the end of the last glacial maximum.
it is thought to be driven by 5 large and about 20 small glacial cycles, but several issues have emerged with this. 1. This includes the preferential loss of the biggest land animals. 2.asynchrony of extinctions across earth(Expected to be the most severe at the outset of Pleistocene 3. Last glacial maximum was not particularly severe. 4. No megafauna extinction in Africa. Also thought to be due to human overkill hypothesis—the idea that places that were newly colonized with humans would coincide with extinction with species, this a lines with Australian fauna and when humans arrived there. Extinctions were least severe in regions where megafauan coevolved with hominids; intermediate in regions whose megafauna experience archaic hominids before being colonized by H. sapiens; and most severe in regions where H. sapiens was the first hominid to colonize the region.
Examples of biogeographic relict endemism
lemurs in Madagascar, marsupials
Examples of paleoendemic species
monotremes
Know the timing of last glacial maximum.
occured from about 26.5 to 19 BP
Know the unique geographic and climatological aspects of oceanic islands.
oceanic islands are islands that have never connected to the mainland. They tend to be small and are surrounded by water which makes temperature fluctuations and seasonality less severe. .
What are the types of endemism for echidna?
paleoendemic and biogeographic relicts
What are the types of endemism for monotremes?
paleoendemic and biogeographic relicts
Examples of Allochthonous endemism
peccary, jaguar
Outline the concept of species area relationships on islands.
relates island area to the number of species it can support. S = cAz or log(S) = log (c) + zlog(A). Where S=Species richness, A=Island Area, C=fitted constant, and z=slope of the line. The steeper the slope of Z the stronger the relationship between area and species richness. As progressively larger areas are sampled, one obtains not only more individuals but also more species, because of some of the new individuals will be representative of rare species that had not yet been seen. Additionally, larger areas will tend to incorporate new kinds of habitats and therefore add specialized species that are restricted to those environments, but at a diminishing rate because of their increased rarity. isolated islands have fewer species per unit area and higher Z values for the species area curve then do sample areas of comparable size on the continents. Small, isolated islands have fewer species incomparable areas on a continent because, if a species becomes too rare in an island it is likely to become extinct, whereas in a continent its population can be to sustained even at low levels by the exchange of individuals between local areas. Thus, as one moves from large to small areas, species richness should decline more rapidly with areas for the more isolated systems. You need a large enough area to pick up representative number of species for the veil line.
Outline the processes that occur at glacial margins.
several species survive at glacial margins with refugium. Formation of ketal lakes. a retreating ice sheet leaves stagnant ice blocks on the outwash plain. Lakes are formed in the glacial outwash and the till by melting blocks of ice. Formation of a glacial plunge pool lake. Glacial meltwater sometimes formed large rivers that flowed over the surface of a retreating glacier, then plunged as much as 3 kilometers down the face of the glacier to carve out a roughly circular basin below.
Explain how the rise of the Isthmus of Panama was a vicariance event for some marine organism.
species like the snapping shrimp were separated by the isthmus of Panama. Therefore instead of having say eight different species you ended up having 16 different species because the isthmus of Panama divided the species in half
Explain the concept of species turnover and be able to provide examples where it has been measured.
species turnover is the number of species on an island that may be determined by area (extinction rate) and isolation (colonization rate), but the identity of species within the total can change. Competitive interactions as new species colonize the an island. Larger islands are able to maintain more species so there is less extinction and vice versa for smaller islands . There's a balance between the extinction rate as determined by the island area and colonization rate determined by island isolation. Turn over species are lost which is linked to island area; Species are gained which is linked to island isolation; And then biotas reaching equilibrium S based on these island characteristics. One example of this is species turnover of birds on the California Channel Islands. These islands have never been connected by a land bridge , and they are off the shore of California. There are various islands with numerous species populations. The number of species at equilibrium and number of species correlated with that equilibrium.
Know some causes of disjunction.
tectonics, intervening extirpation, long range dispersal
Be able to explain how aspects of Earth's orbit (obliquity, eccentricity, and precession) interact to help drive glacial cycles.
the Milankovitch cycles comprise complex combinations in three characteristics of earth's orbit (obliquity, eccentricity, and precession). which together influence insulation or total solar radiation reaching earth, and temperatures (indicated by the ratio of two isotopes of oxygen in ice cores) and in turn drive climatic changes such as the 20 or so glacial interglacial cycles of the Pleistocene epoch. The principle characteristics of earth's orbit that affected its total heat budget in the temporal variation in geographic distribution of that heat are eccentricity (how the shape of the earth orbit deviates from that of a perfect circle), obliquity (the tilt of the earth on its axis), and precession of the equinoxes. Precession involves the orientation of earth axis in the solar system, which affects whether periods of most direct solar radiation occur when earth is at perihelion, aphelion, or some immediate position in its orbit around the sun. With the 41,000 year obliquity cycle dominant early in the Pleistocene, and the longer eccentricity cycle assuming greater importance over the last million years. The descent into an Ice Age thus appears to be driven by these cyclical variations in insulation across the planet, which through various feedback processes result in snowfall accumulations in the northern hemisphere outpacing the rates of snow melt in the summer as the planet gradually cools.
Know the timing of the Pleistocene Epoch on the Geologic Time Scale.
the Pleistocene epoch started about 2.5 million years ago and lasted till about 11,760 years ago
Explain why biogeographic lines between regions, etc., are better thought of as transition zones with aspects of filter dispersal.
the challenges of delineating such boundaries usually reflect a combination of two interrelated phenomena. First, either the historical, geological, and climatic isolation of the regions was originally not so discreet, or it became less discreet falling a major geological transformation, allowing more dispersal between regions and causing the apparent division to be blurred. Second, different groups of organisms respond somewhat differently to the same historical events and climatic patterns, resulting in variability in regionalization schemes among taxa. These two factors have conspired to make it difficult to draw a single line defining the boundary between most regions, including the nearctic and Neotropical regions, some biogeographers are inclined to speak of biogeographic transition zones rather than of discrete lines.
Be able to explain why other taxa discussed in class are considered endemics.
the duck billed platypus is considered endemic because it is only found in a particular area of Australia; Additionally there are other monotremes that are only endemic to Australia which makes them an endemic species
Outline how the slope of the species area relationship should change with area and distance from colonizing sources.
the slope for the species area relationship in log log space is much deeper for isolated islands than for sample areas of different sizes in a single large landmassIsolated islands have fewer species per unit of area and higher Z values for the species area curve than do sample areas of compareable space on the continents. Small isolated islands have fewer species than compareable areas on a continent because, if a species becomes too rare on an island, it is likely to become extinct, whereas in a continent its population can be sustained even at low levels by the exchange of individuals between local areas. The difference between the two curves can be attributed to two factors: first, the great likelihood of extinction without replacement by immigration of rare species on isolated islands, and 2nd the difference in the construction of the two curves, as the New Guinea curve is cumulative species total with the increasing area while the islands datapoints are independent of one another, presenting the species total per island, not a cumulative total.
Explain the processes that drove Pleistocene sea level changes.
there are two different types of changes that drove sea level changes including eustatic and isostatic changes. Eustatic changes are those that are caused by global fluctuations in the volume of liquid water . Isostatic changes are caused by distortion of the underlying asthenosphere due to the weight of the overlying ice. During the last glacial maximum 26 to 19 BP nearly 1/3 of earth's land surface was covered with thick glaciers, while great fields of sea ice occurred in the polar regions. This ice sheet form may shun remove the large volume of water from the ocean, probably exceeding the equivalent of 50 million kilometer cubed of ice. This resulting drop and mean sea level has been estimated between 125 and 134 meters below current sea level as greater than at any other point in the place to scene. The total amplitude of eustatic sea level changes during the Pleistocene may have been around 150 to 160 meters, although as noted above there can be pronounced local and regional discrepancies from the average trends. The record throughout the place to scene illustrates the repeated in very rapid transitions between full glacial and interglacial conditions and the resultant changes in sea level. In addition to these global changes in sea levels, regional sea levels also varied substantially as earths crust rose and sank in the asthenosphere.
Understand how biogeographic realms and regions are delineated.
they are divided through provincialism, but most closely related species tend to have overlapping or adjacent regions. Specific higher order taxa show similar patterns of endemism. the first two patterns demonstrate nonrandom distributions which are local origins and distributions. the fonz law is environmentally similar locations with different biotas. There is a hierarchy of realms slash regions, subregions come provinces, districts
Explain how geographic scale and taxonomic distinctness are important in defining a specific taxon as being endemic.
this is important in the idea of different types of mice that live around the world from the family Heteromidae. This is because there are different species poo are endemic to different parts of the world. So while the entire family is found from as far north as Canada, down to the tip of South America, each individual species cannot live in all of those Rangers because they aren't endemic to that area and so they cannot tolerate the conditions in that particular area. therefore one species is endemic specifically to the Great Basin, however there are some species that are endemic to just Mexico. Higher taxa tend to have fairly broad distributions within a continental landmass, presumably reflecting the ancient origin and long confinement of major lineages, while more recently differentiated taxa tend to be confined to smaller areas. As pointed out earlier, nested patterns are required by the hierarchical classifications of bold organisms and biogeographic regions, since apparent pattern could be an artifact of based merely on taxonomic classification.
Be able to explain in general how changes in sea level affected plant and animal distributions.
this salt water corridor provided a dispersal avenue for shoreline flora of the Atlantic coast. Subsequent rebounding of Earth's crust by as much as 275 m drained this corridor and transformed it into the freshwater Saint Lawrence river, which drains the great lakes. Events such as this may account for the disjunct ranges of many species adapted to coastal marine environments. The existence of such transient corridors explains the disjunct distributions of may shallow-water, marine, and estuarine species along the coastlines of easter North America and the great lakes. Although there was much variation within taxonomic groups, plants tended to shift more slowly than animals. The geographic dynamics of species during the Pleistocene created many isolated populations, in some cases promoting evolutionary divergence and diversification of lineages. Many plants and animals that were unable to track their shifting environments were able to remain in situ by adapting to altered conditions, while others adapted and evolved en route—that is , during shifts to other regions. The remaining species, unable to shift or adapt went extinct. Extinctions were much more common among plants than animals, during the initial cycles of climatic reversals.
Be able to explain why Devil's Hole pupfish is considered endemic.
this species is endemic because it is only found in one area in Nevada. It is the entire native habitat of the devil's hole pupfish.
Be able to explain why biogeographers have long been interested in studying island systems.
throughout much of its history, island biogeography has focused on two general patterns: the tendency for species richness of insular biotas to increase with island area, and a tendency of species richness to decrease with island isolation - patterns known by the species area relationship and the species isolation relationship. any single contribution can be said to have triggered the revolution and ecological biogeography that took place in the 20th century it was Robert MacArthur and Edwin Wilson's equilibrium model of island biogeography. their theory provided an elegantly simple in general model that both accounted for known patterns and species richness and generated novel predictions. What did the early emphasis of island biogeography was placed within debates about historical connections between regions and whether island endemics were stranded relics or the products of situ evolution. hence much of the work was considered with idiographic questions such as where a particular taxonomic the organisms originated, and how, as a result of subsequent dispersal, speciation, and extinction in particular regions, of diversity and distribution changed.
Be able to explain why cui
ui is considered endemic-this species is only found in Pyramid Lake in Nevada. Previously there was another like that they would travel to before they went through a population bottleneck because the area was dried up and logged . It is specific to 1 area (the Great Basin), other species similar to it are found in other lakes.
Know some examples of catastrophic flooding from the break
up of ice dams in the late Pleistocene.-Lake Agassiz formed in the late Pleistocene. At the top by northern Canada there was the extent of the previous Laurentide ice sheet. This lake formed around 9,000 bp and the ice damn that was holding the water back from flooding out to sea broke. Above 163,000 km^2 of water moved out to the Atlantic. Additionally, some of this water flowed out through the great lakes as well. Similarly a glacial lake Missoula formed from the cordilleran ice sheet melting. When it broke it flushed all the way out to the pacific ocean.
Have a general idea of the timing of events before, during, and after the Great American Biotic Interchange (GABI).
when it formed 3.5 Ma. When the Central American Archaea plasia was uploaded to form a continuous land bridge, many organisms invaded and dispersed along it. Because the climate and habitats of Central America and southern Mexico or tropical, there was much biotic exchange between that area in tropical regions of northern South America. Thus, even though Central America and southern Mexico have many endemic forms, there usually recognizes a subregion of the neotropics. When South America was isolated there was a distinct and endemic mammal fauna evolved. This fauna included one monotreme, several groups of marsupials, large carnivores, and several lineages of eutherians that differentiated to produce a morphologically and ecologically diverse fauna, including large herbivores. This radiation was in some ways comparable to, but even more diverse than that which occurred on Australia and Madagascar, the other island continents formed by the breakup of Gondwana. Since its formation, the Central American land bridge has served more as a filter than as a corridor for dispersal. The overall diversity of South America fauna increase because of the invasion, establishment, and subsequent diversification of lineages from North America. the magnitude of change was even greater than the final figures for generic or familial diversity suggest however because of several endemic South American forms went extinct. she's included several large marsupial carnivores and even larger you theory and herbivores