BIO 3003G Introduction to Evolution - Chapter 11

Vertebrate animals

- The most ancient group of vertebrates are fish, which evolved first in the oceans. - Tetrapod (4-footed) vertebrates evolved from a type of fish about 390 million years ago. - The earliest tetrapods were aquatic. - Shortly after the first terrestrial (land living) tetrapods evolved. - The tetrapod vertebrates include amphibians, reptiles/birds and mammals. Some tetrapods, e.g. snakes and whales/dolphins, don't have any legs or they have vestigial limbs. - The first vertebrates were jawless fish. - Jawless fish evolved into a variety of kinds of fish including the extinct ostracoderms and their descendants the extant lampreys. - One group of jawless fish evolved a jaw (mandible) and diversified into numerous species. - - As shown in figure on the next slide, the jawed fish branched into cartilaginous fish and bony fish. The cartilaginous fish are the sharks and their relatives, they have skeletons made of cartilage. - - Ancient bony fish, called bony because their bones were ossified (calcified), evolved into two major groups the ray finned fish and fleshy (lobed) finned fish. The ray finned fish make up over 20,000 of the approximately 65,000 extant vertebrate species, they are by far the most diverse group of vertebrates.

Taxon (plural Taxa)

a taxonomic unit at any level of classification

Monotremes

a very small group that is made up of duckbilled platypuses and echidnas. retained a few other ancient characteristics.

Gene regulation

ability of an organism to control which genes are transcribed in response to the environment emerged as a central mechanism explaining developmental and evolutionary change.

Ediacaran organisms

alternative (and earlier) evolutionary experiment in multicellularity and not ancestors of modern multicellular organisms. The diverse anatomies of the Ediacaran organisms occurring in the same deposits attests to the diversity of species and ecosystems present in the Precambrian. Based on fractal repeats of a frond structure - rangeomorphs one of the Ediacaran species

Marsupials

named for the pouch the female broods her young in. Young marsupials are born after a very short gestation and must finish embryonic development while nursing.

Geologic Conditions - possible cause of Cambrian Radiation

physical cause of the Cambrian explosion may have been plate tectonics and the resulting changes in the shape, extent and latitude of shorelines, climate and environment. Sea level changes that accompany glaciations also would have played a role by opening up new environments.

______ _______are named for the organ formed from maternal and embryonic tissue that allows nourishment, oxygen and nutrients to reach the embryo and waste products to be passed to the mother for disposal.

placenta mammals

Taxonomy

principles and procedures used in classifying organisms.

adaptive radiation

rapid evolution of species in which many new ecological opportunities were made available for organisms with the capacity to evolve in diverse ways to occupy and exploit the changing environments occurred during the cambrian period.

Amniotes are __________ and mammals.

reptiles

Animals Ingest other organisms to get energy

sets them apart from the other multicellular eukaryotes, plants and fungi. Plants obtain energy through photosynthesis and fungi absorb their food

brachiopods.

shell forms of mollusks and a related phylum called

All animals are heterotrophic

they must ingest other organisms to get energy.

Caecilians is an amphibian

this type of amphibian is shaped like a worm or snake; has bony scales; small eyes under their skin; blind; live in tropical areas. mostly burrowing tropical, legless amphibians. usually limited to either habitats in or around freshwater or moist terrestrial habitats because they have delicate scale-less skin that must be thin so blood vessels can come near the surface. likely lost their limbs because they interfered with their mode of burrowing. They rely on their skin as a secondary respiratory organ where oxygen can diffuse into blood vessels and carbon dioxide can diffuse out of their blood into the air through their skin. Another factor that restricts them is that they have delicate shell-less fish like eggs that are usually only protected by a gelatinous material. These eggs easily desiccate killing the embryos within.

Some_______________reptiles (i.e. boas) give birth instead of laying eggs and of the 5,500 mammals all but a handful give birth. Even though some no longer give birth the same membranes are still present around the embryos as they develop.

Amniotes

Live in Arid ecosystems and usually only active at night during rainy seasons.

Amphibians

Some _______ give birth instead of laying eggs.

Amphibians

Ediacaran Biota

An early group of soft-bodied, multicellular eukaryotes known from fossils that range in age from 565 million to 545 million years old. debatable whether any of the Ediacaran Biota are animals Some resemble jellyfish, others perhaps segmented worms and mollusks. haven't detected any anatomical structures typical of animals, e.g. eyes, mouths, anuses, digestive tracts, or locomotory structures. deposit, and its biota, were named after where they were discovered, the Edicaran hills in South Australia

Insects:

The largest single group of arthropods. New species are constantly being discovered and estimates of the total number of distinct insect species are in the millions, perhaps as many as 20 million. Most insects have 4 wings, though some have lost them. Insect life cycles are often complex. Larvae may have to undergo a drastic metamorphosis of anatomy in order to reach maturity, as with butterflies or the fly species below. A major hurdle to the evolution of terrestrial organisms is limiting water loss, the exoskeleton of insects limits dehydration

Rising oxygen levels - possible cause of Cambrian Radiation

The build up of oxygen in the atmosphere began a billion years before the Cambrian as the result of photosynthesis by cyanobacteria. All animals need oxygen because they have an aerobic metabolism, though some can survive extended periods of dormancy without oxygen. The reason they need oxygen is because it is needed for chemical reactions in their mitochondria that convert food molecules they have taken in into a high energy type of molecule used to do work (build, break down, and move things) in their cells. The aerobic metabolism of animals would have required oxygen to have reached 1% of the atmosphere, which is believed to have happened in the early Cambrian. Oxygen in the form of O3 (ozone) forms a protective layer (ozone layer) that could have facilitated the radiation of animals in shallow water habitats (tide pools and nearby rocky surfaces).

Regional Identity - possible cause of Cambrian Radiation

The gradient of morphogens put in the egg by the mother helps control which genes are turned on and when. As the embryo goes from one cell to two, then two to four and so on different cells and groups of cells end up with different concentrations of morphogens. Mutations in homeobox (or homeotic) genes can have catastrophic results for developing embryos

Single-celled ________ that existed as colonies either were animal ancestors or _____ and ______descended from a common protistan ancestor.

Single-celled choanoflagellates choanoflagellates animals

Omnivores

Consumers that eat both plants and animals.

Carnivores

Consumers that eat only animals

Herbivores

Consumers that eat only plants

Mammals

Warm blooded animals that have hair and produce milk for their young

Causes of Cabrian Radiation

1) Geological conditions were favorable 2) Rising Oxygen Levels 3) Predator-Prey Relationships 4) Evolution of embryonic development and body plan specification 5) New sources of genetic variation and changes in gene number and regulation

Three surviving types of mammals

1) monotremes, 2) marsupials 3) placental mammals.

Placental mammals

Animals whose young are born and where the embryo develops internally in a uterus connected to the mother by a placenta where nutrients diffuse from mother to embryo; also called eutherians

Shared Embryonic Development and Body Plan Specification - possible cause of Cambrian Radiation

Axes of symmetry, usually anterior-posterior (head end to tail end) and dorsal-ventral (back to front) patterning is the result of gene products (morphogens) deposited in the egg by the mother at different concentrations in different parts of the egg (Figure 11.7) Paired appendages Shared similar tissues and organs Homeobox genes, many shared among eumetazoans provide the primary signals and initiate the pathways that pattern body regions and the formation of particular structures.

Animal reproduction

Both asexual and sexual reproduction occurs in animals, and sometimes both can occur in the same species.

Predator-Prey Relationships - possible cause of Cambrian Radiation

Changing modes of feeding, facilitated by rising oxygen levels, may have helped spur increasing diversity of organisms. Predators feeding on the most abundant prey species reduce its numbers opening up resources for other species helping diversity to evolve.

Cambrian "Explosion"

Diversity of organisms could be interpreted as adaptive radiation 1) new ecological opportunities were made available for organisms with the capacity to evolve in diverse ways to occupy and exploit the changing environments 2) Adaptive radiation - rapid evolution of speceis 3) Based on molecular clock estimates the first animal evolved around 700 million years ago.

545 Mya

Early Cambrian Explosion

_______ ______ appears in the Upper Precambrian-Lower Cambrian some 565 Mya

Ediacaran Biota

Monotremes

Egg laying mammals

Amphibians

Examples: Frogs, toads, salamanders and caecilians Caecilians are a group of mostly burrowing tropical, legless amphibians. Like snakes their ancestors likely lost their limbs because they interfered with their mode of burrowing. Extant amphibians are usually limited to either habitats in or around freshwater or moist terrestrial habitats. Amphibians are limited to these areas because they have delicate scale-less skin that must be thin so blood vessels can come near the surface. They rely on their skin as a secondary respiratory organ where oxygen can diffuse into blood vessels and carbon dioxide can diffuse out of their blood into the air through their skin. Another factor that restricts them is that they have delicate shell-less fish like eggs that are usually only protected by a gelatinous material. These eggs easily desiccate killing the embryos within.

Thylacosmilis

Extinct saber-toothed predatory marsupial from South America. Much more closely related to opossums, kangaroos and koalas than they were to the saber toothed felines

Structures typical of animals

Eyes Moths anuses digestive tracts locomotory

Amniotes

Group of early tetrapods evolved a new type of egg, the amniotic egg. Inside this egg the embryo is wrapped in a series of membranes that hold food (yolk), water, perform respiration and store waste they make as they develop. Example: The mammals that lay eggs are the duckbilled platypus and echidnas. member of a clade of tetrapods that have an amniotic egg containing specialized membranes that protect the embryo; mammals, birds+reptiles

bricolage (tinkering)

Jacob refered to evolution as this term that rightly places the emphasis on modification of existing genes.

Arthropods

Insects, crustaceans and spiders and relatives If success of a group is measured by number of species arthropods, particularly insects, are the most successful group of animals by a wide margin. Two important characteristics of arthropods are the presence of an exoskeleton and jointed appendages (including legs) Their exoskeleton is secreted by and covers their skin and provides support and protection, it is mostly made of chitin (a tough carbohydrate) and waxy lipoproteins.

_____ evolved from ancient reptiles called mammal like replites

Mammals

Marsupials

Mammals whose immature offspring complete their development in an external pouch.

beginning of the Cambrian, 545 Mya,

Many different types of Animals present

Placenta mammals are born _____ developed than marsupials. May explain why they are more successful.

More

Birds are also ____________. Last survivng branch of ___________

Reptiles (Amniotes) Dinosaurs

Examples of placenta mammal

Rodents, primates, carnivores (felines, canines, bears, weasels), bats whales and dolphins, all hoofed mammals, elephants and many others are included in this group.

Mollusks:

Snails and slugs, bivalves (clams, oysters etc..) and cephalopods (octopuses, squids, cuttlefish and nautili) • Soft bodies animals, many of which are protected by a shell. • Almost all species are aquatic, only some snails and slugs can live on land. • Bivalves have evolved into sedentary or sessile filter feeders that pump water through their body and strain out the materials they need. • Cephalopods are active predators. The cephalopods include the most intelligent of all the invertebrate animals, octopuses and cuttlefish. • Octopuses and cuttlefish are capable of remarkable camouflage. - An invertebrate is an animal that doesn't have a backbone.

believed that the earth was encased in a sheet of ice 1 km thick (snowball Earth) two to four times between 725 and 635 Mya, limiting evolution

Snowball Earth

Sponge anatomy

Sponges have a series of small holes that open into tubes that run through their body. The small tubes connect with larger holes. Flagellated cells line the tubes running through their body and pump water through the tubes by beating their whip-like flagella. Water enters their body through the smaller holes and leaves through the larger ones. - Flagella are hair-like extensions used for locomotion by some single celled organisms, in the case of sponges their flagellated cells propel water through their tube system.

Stem Taxa

Stem taxa are the first members of a particular group

Fleshy (lobe) finned bony fish

There are only a handful of surviving members of this group, like the lungfish above, but they were a diverse group in the distant past. Tetrapods evolved from a long extinct group of flesh finned fish, the modern fleshy finned fish are distant cousins of the tetrapod vertebrates they are NOT ancestors of tetrapods. The limbs of tetrapods (legs, arms, wings) are modified pectoral and pelvic fins. This is strongly supported by the fossil record, which shows a transition from fin to legs occurring through several ancient fleshy finned fish species. Genetics of fish and tetrapods also supports this, because the same genes are responsible for forming pectoral and pelvic fins and tetrapod limbs. The first tetrapods evolved in freshwater and then evolved into a variety of species, some of which were terrestrial (land living) species. The living tetrapod groups are descended from one of the early groups of tetrapods, the others went extinct without leaving descendants.

Radiata (cnidarians):.

This group includes jellyfish, sea anemones, corals and many others, including a small freshwater species common in pond in Illinois called hydra • Cniarians have soft sac-like bodies, they have no hard skeleton instead their body is supported by a hydrostatic skeleton. This water skeleton works like a water balloon, the more water they take into their body the firmer they become. They can push water out of their body cavity to make themselves much smaller. • Cnidarians have some tissue types, like nerve cells, but lack the organs and complex organ systems found in most eumetazoa. • Cnidarians lack a brain and yet they can be very effective predators because of special cells called cnidocytes. • Cnidocytes contain barbed threads that have poison in them. When something brushes up against a cnidarian the barbs shoot out of the cnidocyes and sting. These stinging cells are located by the millions on their tentacles.

- The absence of any fossilized larval stages strongly suggests that early animals developed directly without a larval stage; that is, they had direct development. no metamorphosis

True

Genetic evidence supports the relatively close relationship between animals and the extant choanoflagellates.

True

Burgess shale deposit dates to 545 million years ago.

Yoho National Park, British Columbia, Canada are unique taxa that already had evolved the characters that define the phyla of living animals. Morphological gaps separated these taxa. Origination of phyla from stem taxa of the various animal phyla has to be sought in earlier forms in older deposits. Ancestors of the major animal phyla, including the one that includes us and other vertebrates, appear in this Cambrian deposit.

Marsupials

______ are named for the pouch the female broods her young in. Young are born after a very short gestation and must finish embryonic development while nursing.

Amniotes

______ egg also has something amphibian eggs lack a tough leathery or hard shell that allows it to be laid in dry places, unlike the shell less amphibian eggs.

Animals evolved from

a choanoflagellate protist of some kind that lived in clumps or colonies of clones

Bilaterally symmetrical

animals are eumetazoans ("advanced" animals) are ones that can be divided into two equal mirrored halves by dividing them down the middle of their body • Examples of bilaterally symmetrical animals - Vertebrates, arthropods (insects, crustaceans, spiders), mollusks and the many worm-like groups of animals • Bilaterally symmetrical animals are usually cephalized.

Pangolin

anteater-like placental mammal. What look like scales are agglutinated hairs

Most animals

are mobile at some time in their life

Cephalized animals

are ones that have a concentration of nervous and sensory structures at the anterior end of their body, in other words they have a head.

Simplest animals

are the sponges, called the parazoa. - Sponges are filter feeding, sessile (cannot move) as adults, aquatic organisms. - A filter feeding animal is one that filters its food and the nutrients it needs out of the water. - They are very simple and lack organs and organ systems. - They have handful of cell types that carry out all functions.

eumetazoa

bilaterally symmetrical, this means their bodies can be divided into two equal mirrored halves. well-defined tissues, diploblastic, triploblastic AKA advanced animals have tissue types, organs, organ systems and a head. vast majority of animals are in this group including.... - Vertebrates (animals with a backbone and skull) -Arthropods (insects, crustaceans, spiders, etc..) -Molluscs (snails, slugs, clams, oysters, octopuses, cuttlefish) -Earthworms, leaches and relatives -Flatworms -Starfish, sea urchins and relatives -And many other more obscure animal phyla (groups) trace back to a worm-like common ancestor that had a head, two eyes, a pair of antennae, and a segmented body with repeating similar sections.

Animals don't have cell walls

depend on either the buoyancy of water or some kind of skeletal system for support.

animal groups first evolved in the oceans, some later

expanded to freshwater or land

Homeobox genes (homeotic)

genes that code for transcription factors that activate other genes that are important in cell development and differentiation mutation is these genes can have catastrophic results for developing embryos Duplications of some of these genes have resulted in important changes in body organizations of different animal groups. Several major conclusions come from comparative study of homeobox genes across the animal kingdom. 1) These important developmental (regulatory) genes all share a common, highly conserved sequence (meaning relatively few differences between them across species). 2) A common genetic evolutionary origin underlies the conservation of the basic developmental pathways that establish animal body plans. 3) What has changed with evolution of these groups is context; these genes are turned on at different times and in different patterns in different animals.

Chordates:

group includes the vertebrate animals and some invertebrate (no backbone) relatives of theirs. Like all other major groups of animals chordates, including vertebrates evolved in the oceans. Every animal with a backbone traces back to a common ancestor that was a type ancient fish. All vertebrates share a variety of traits, two important ones are 1) spinal column (vertebral column) that surrounds and supports their spinal cord and serves as the central axis of support of their endoskeleton (internal skeleton of bones) 2) skull: which surrounds and protects their brain The vertebrates include the various groups of fish, amphibians, reptiles/birds and mammals. There are about 65,000 extant vertebrate species.

Annelids:

group of invertebrates that includes earthworms and leeches. - On the slide about eumetazoa I mentioned segmentation. - Segmentation is visible on the outside of annelids. - In vertebrates, like us, it is less obvious, but still present in the arrangement of our vertebrate and nerves along the spine.

molecular clock

looks at pieces of non-coding DNA where mutations are expected to build up randomly, but at a predictable rate. Species are compared for those shared sections and the number of differences are counted, them more differences there are the longer they probably split from their last shared common ancestor Model that uses DNA comparisons to estimate the length of time that two species have been evolving independently

Phylum (plural Phyla)

major taxonomic category below the level of kingdom, used to include classes of organisms that may be phenotypically quite different but share same general characterisitcs or body plan

All animals are made up of

many cells

only evidence used to classify early Cambrian organisms is ________

morphology (anatomy)

choanoflagellates

single celled organism that lived in colonies

Eumetazoa: All animals except ________________

sponges