Bio 104S Ch 24 - Origin of Species

Speciation can occur in two ways:

Allopatric speciation Sympatric speciation

If hybrids do not become reproductively isolated from their parent species, then three alternate outcomes are possible: 1. Reinforcement 2. ___ 3. ___

Fusion, Stability

__ __ between populations holds a species together genetically

Gene flow

___ ___ reveal factors that cause reproductive isolation

Hybrid zones

___ is the cumulative effect of many speciation and extinction events. Macroevolution is evolutionary change above the species level; includes the origin of new groups of organisms, and the impact of mass extinctions on the diversity of life and its subsequent ___

Macroevolution, recovery

Morphological differences can prevent successful completion of mating [isolation]

Mechanical

consists of changes in allele frequency in a population over time

Microevolution

the presence of extra sets of chromosomes due to accidents during cell division; this can make a new species in one generation

Polyploidy

Sympatric speciation can occur if gene flow is reduced by factors --including: ____ Sexual selection ____ differentiation

Polyploidy, habitat

Reduced hybrid viability Reduced hybrid fertility Hybrid breakdown are qualities of _____ barriers

Postzygotic

block fertilization from occurring by Impeding different species from attempting to mate, Preventing the successful completion of mating, Hindering fertilization if mating is successful

Prezygotic barriers

The fossil record includes examples of species that appear suddenly, persist unchanged for some time, and then disappear. ___ ___ describes these periods of apparent stasis punctuated by sudden change. The punctuated equilibrium model contrasts with a model of ___ change in a species over time

Punctuated equilibria, gradual

the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring

Reproductive Isolation

____ populations may evolve independently through mutation, natural selection, and genetic drift.

Separated

___ selection can drive sympatric speciation

Sexual

___ can take place with or without geographic separation

Speciation

forms a conceptual bridge between microevolution and macroevolution

Speciation

the process by which one species splits into two or more species, is at the focal point of evolutionary theory

Speciation

an example of ____ speciation is when organism is in environment but they don't mate because of selective reproduction; female preference

Sympatric

Species that breed at different times of the day, different seasons, or different years cannot mix their gametes [isolation]

Temporal

Bacteria reproduce primarily in an asexual manner. Accordingly, which species concept is difficult to apply to bacterial species? a. biological species concept b. morphological species concept c. ecological species concept d. none of the above

a

Bird guides once listed the myrtle warbler and Audubonʹs warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow -rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification? A) The two forms interbreed often in nature, and their offspring have good survival and reproduction. B) The two forms live in similar habitats. C) The two forms have many genes in common. D) The two forms have similar food requirements. E) The two forms are very similar in coloration.

a

In ___ speciation, gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations

allopatric

the flightless cormorant of the Galápagos likely originated from a flying species on the mainland. This speciation is an example of

allopatric

In ___ speciation, geographic isolation restricts gene flow between populations. In ___ speciation, a reproductive barrier isolates a subset of a population without geographic separation from the parent species.

allopatric, sympatric

Sympatric speciation can also result from the ___ of new ecological niches

appearance

Sea urchins are broadcast spawners: They release their gametes into the water without courtship. Which of these reproductive isolation mechanisms is most likely affecting sea urchins? a. behavioral isolation or mechanical isolation b. gametic isolation or temporal isolation c. habitat isolation

b

Several species of amphibians are able to read each other's mating rituals and understand them, tend to be fertile at the same time, and are usually similar in size. However, when they attempt to mate, they never produce offspring. Which of the following barriers is most likely the cause of this? a. behavioral isolation b. gametic isolation c. reduced hybrid fertility d. hybrid breakdown

b

The fossil record shows that many species remain constant for long periods of time, but then speciation episodes occur rapidly. This is best described as _____. a. gradualism b. punctuated equilibrium c. allopatric speciation d. sympatric speciation

b

The fossil record shows that species remain constant for long periods of time, but then speciation episodes occur rapidly. This is indicative of a) gradualism. b) punctuated equilibrium. c) allopatric speciation. d) sympatric speciation.

b

The largest unit within which gene flow can occur? a) population b) species c) genus d) hybrid

b

When differentiating between two species of fish, you notice that one species stay near the surface and feed on floating algae, while the other species are bottom feeders. This is using the a. morphological species concept. b. ecological species concept. c. phylogenetic species concept.

b

Courtship rituals and other behaviors unique to a species are barriers to mating [isolation]

behavioral

Reproductive barriers are intrinsic to the organisms themselves; physical separation alone is not a ___ barrier

biological

According to the punctuated equilibria model, A) natural selection is unimportant as a mechanism of evolution. B) given enough time, most existing species will branch gradually into new species. C) most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species. D) most evolution occurs in sympatric populations. E) speciation is usually due to a single mutation.

c

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian islands have different elaborate courtship rituals that involve fighting other males and stylized movements that attract females. What type of reproductive isolation does this represent? A) habitat isolation B) temporal isolation C) behavioral isolation D) gametic isolation E) postzygotic barriers

c

Microevolution occurs within populations. Macroevolution is thought of as the patterns of change that occur between taxa. Which is an example of speciation? a. microevolution b. macroevolution c. both d. neither

c

The biological species concept relies on a disruption of which aspect of population genetics? a. mutation b. selection c. gene flow d. genetic drift e. all of the above

c

The cichlid Cynotilapia afra, introduced at West Thumbi Island in Lake Malawi in the 1960s, has split into two genetically distinct populations, located at the north and south ends of the island. How can scientists determine whether these populations are now different species, according to the biological species concept? a) See whether the two populations are morphologically different from each other: coloring, bone structure, and so on. b) Determine whether captured individuals from the two different populations will mate and produce offspring in a laboratory fish tank. c) Determine whether individuals from one population will interbreed with individuals from the other population when introduced into each other's native habitats.

c

You spot a sea snake while you are in a boat on the ocean and remark about how similar it looks to a snake that lives in central Illinois. However, you know that they are most likely separate species due to which of the following reproductive barriers? a. behavioral isolation b. gametic isolation c. ecological/habitat isolation d. temporal isolation

c

Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be A) 12. B) 14. C) 16. D) 28. E) 56.

d

The fossil record includes examples of species that appear suddenly, persist unchanged for some time, and then ____

disappear

Reproductive isolation may arise as a by-product of genetic ___. (For example, isolated populations of mosquitofish have become reproductively isolated as a result of selection under different levels of predation)

divergence

Which of the following factors would not contribute to allopatric speciation? A) A population becomes geographically isolated from the parent population. B) The separated population is small, and genetic drift occurs. C) The isolated population is exposed to different selection pressures than the ancestral population. D) Different mutations begin to distinguish the gene pools of the separated populations. E) Gene flow between the two populations is extensive.

e

The ecological species concept defines a species in terms of its ___ niche. It applies to sexual and asexual species and emphasizes the role of ___ selection

ecological, disruptive

Gene flow can occur between morphologically and ____ distinct species (For example, grizzly bears and polar bears can mate to produce "grolar bears")

ecologically

Sperm of one species may not be able to fertilize eggs of another species [isolation]

gametic

The biological species concept cannot be applied to fossils or asexual organisms (including all prokaryotes); it emphasizes absence of ___ ___

gene flow

If hybrids are as fit as parents, there can be substantial ___ ___ between species If gene flow is great enough, reproductive barriers ___ and the parent species can fuse into a single species. (For example, pollution in Lake Victoria has reduced the ability of female cichlids to distinguish males of different species from males of their own species.)

gene flow, weaken

Speciation can occur rapidly or slowly and can result from changes in few or many ___

genes

In allopatric speciation, ___ isolation restricts gene flow between populations -reproductive isolation may then arise as a by-product of genetic changes resulting from divergent natural selection, ___ ___, or sexual selection -even if contact is restored between populations, interbreeding is prevented

geographic, genetic drift

Biologists compare morphology, physiology, biochemistry, and DNA sequences when ___ organisms

grouping

Species encounter each other rarely (or not at all), because they occupy different habitats (but not isolated by physical barriers) [isolation]

habitat

____ selection occurs when differences among individuals cause them to choose different habitats

habitat

the offspring that results from mating between different species

hybrid

Some first-generation hybrids are fertile, but when they mate with each other or with either parent species, offspring of the next generation are feeble or sterile

hybrid breakdown

Hybrids often have reduced fitness compared with parent species. The distribution of ___ ___ can be more complex if parent species are found in patches within the same region

hybrid zones

Hybrids are the result of mating between species with ___ ___ barriers

incomplete reproductive

Regions with many geographic barriers typically have more species than do regions with fewer barriers. Reproductive isolation between populations generally ___ as the distance between them increases

increases

The interval between speciation events can range from 4,000 years (some cichlids) to 40 million years (some beetles), with an average of 6.5 million years. -speciation rarely took less than 500,000 years -important implications for recovery from ___ ___ -variability in speciation events also indicates that there is no "speciation clock"

mass extinctions

Many questions remain concerning how long it takes for new species to form and how many genes need to differ between species. The rate of speciation can be studied using the fossil record, morphological data, or ___ ____

molecular data.

Polyploidy is much more common in ___ than in ___

plants, animals

The definition of barrier depends on the ability of a ___ to disperse (For example, a canyon may create a barrier for small rodents, but not birds, coyotes, or pollen)

population

prevent the hybrid zygote from developing into a viable, fertile adult by

postzygotic barriers

The ___ pattern in the fossil record and evidence from lab studies suggest that speciation can be rapid. (For example, the sunflower Helianthus anomalus was formed by hybridization between two other sunflower species followed by ___ speciation.)

punctuated, rapid

Even if hybrids are vigorous, they may be sterile

reduced hybrid fertility

Genes of the different parent species may interact and impair the hybrid's development or survival in its environment

reduced hybrid viability

Macroevolution

refers to broad patterns of evolutionary change above the species level

When hybrids are less fit than parent species, ____ of reproductive barriers may occur through strong selection for prezygotic barriers. Over time, the rate of hybridization ____

reinforcement, decreases

The biological species concept emphasizes ___ isolation

reproductive

In monkey flowers (Mimulus), at least two loci affect flower color, which influences pollinator preference. Pollination that is dominated by either hummingbirds or bees can lead to ___ ___ of the flowers. In other organisms, speciation can be influenced by larger numbers of genes and gene interactions

reproductive isolation

In sympatric speciation, a ____ barrier isolates a subset of a population without geographic separation from the parent species. Sympatric speciation can result from ___, natural selection, or sexual selection

reproductive, polyploidy

Extensive gene flow from outside the hybrid zone can overwhelm ___ for increased reproductive ___ inside the hybrid zone (For example, parent species of Bombina routinely migrate into the narrow hybrid zone, resulting in ongoing hybridization)

selection, isolation

Many species definitions have been proposed; the usefulness of each depends on the ___ and the research questions being asked.

situation

A fundamental question of evolutionary biology persists: How many genes influence the formation of new species? Depending on the species in question, ___ might require change in a single gene or many genes. For example, in Japanese Euhadra snails, the direction of shell spiral affects mating and is controlled by a single gene

speciation

The morphological species concept defines a species by ___ features. It applies to sexual and asexual species but relies on ___ criteria

structural, subjective

In ___ speciation, speciation occurs in populations that live in the same geographic area

sympatric

Where reinforcement occurs, reproductive barriers should be stronger for ___ than ____ species.(For example, female flycatchers in the genus Ficedula recognize and select mates of their own species when choosing between males from sympatric populations. Female flycatchers frequently make mistakes when selecting males from the more similar allopatric populations)

sympatric, allopatric

The biological species concept states that a species is a group of populations whose members have the potential to

to interbreed in nature and produce viable, fertile offspring

Other species concepts emphasize the unity ___ a species rather than the ___ of different species

within, separateness