BIOL-182: Evolution of Life - Animals Review Flashcards

A comprehensive set of 30 flashcards reviewing key concepts, definitions, and clades from BIOL-182 Animal Evolution lectures.

According to Mora et al. (2011), how many animal species are estimated to exist on Earth?

7.77 million

What external protein provides structural extracellular support in animal cells, which lack cell walls?

Collagen

How is evolution concisely defined in the lecture material?

Descent with modification

In a phylogenetic tree diagram, what feature represents the common ancestor for the entire tree?

The root

What is the primary criterion for defining species according to the biological species concept?

The potential to interbreed and produce viable, fertile offspring

What species of snake is cited as an example of an asexual organism that cannot be evaluated using the biological species concept?

Indotyphlops braminus (flowerpot snake)

What are two major advantages of the morphological species concept?

It can be applied to both asexual and sexual organisms, and it can be useful without information on gene flow.

How does the ecological species concept define a species?

In terms of its ecological niche

What is the function of prezygotic reproductive barriers?

To block fertilization from occurring between members of different species

What three postzygotic barriers can contribute to reproductive isolation after a hybrid zygote is formed?

Hybrid unviability, hybrid infertility, and hybrid breakdown

What distinguishes allopatric speciation from sympatric speciation?

Allopatric speciation involves geographic isolation, whereas sympatric speciation occurs without geographic separation.

What genetic condition describes the tetraploid tree frog Hyla versicolor ($4n$) compared to the diploid Hyla chrysoscelis ($2n$)?

Polyploidy

What three common outcomes can occur in a hybrid zone over time?

Reinforcement, fusion, and stability

In the European hybrid zone between Bombina bombina and Bombina variegata, where does each toad species typically live?

Bombina bombina (fire-bellied toad) lives at lower altitudes, while Bombina variegata (yellow-bellied toad) lives at higher altitudes.

What proportion of all known animal species are beetles?

One in four animals known to science is a beetle.

What percentage of species in the animal kingdom do invertebrates comprise?

Almost 95%

What is the chronological sequence of early animal embryo development stages following fertilization?

Zygote -> Cleavage -> Eight-cell stage -> Blastula -> Gastrulation -> Gastrula

Which embryonic germ layer develops into skeletal muscle, bones, connective tissue, and the heart?

Mesoderm

What structures develop from the ectoderm during embryonic development?

Skin, hair, mammary glands, and the nervous system

How is a true coelom defined in triploblastic animals?

A body cavity completely lined by tissue derived from mesoderm

How does a hemocoel differ from a true coelom?

A hemocoel is lined by tissue derived from mesoderm and tissue derived from endoderm.

What are the characteristics of cleavage and the fate of the blastopore in protostome development?

Cleavage is spiral and determinate; the mouth develops from the blastopore.

What are the characteristics of cleavage and the fate of the blastopore in deuterostome development?

Cleavage is radial and indeterminate; the anus develops from the blastopore.

What group of conserved genes regulates the development of animal body form?

Hox genes

What organism group is identified as the most recent common ancestor of living animals?

Choanoflagellates

What three factors are hypothesized to have triggered the Cambrian explosion (~535-525 mya)?

Increased atmospheric oxygen, the evolution of predator-prey relationships, and the origin of Hox genes.

What is the name of the 508-million-year-old fossil organism from the Cambrian explosion shown in the lecture slides?

Hallucigenia

In phylum Porifera, what specialized cells generate water current for filter feeding, and what main opening does water exit through?

Choanocytes (collar cells) generate the water flow, and water exits through the osculum.

What specialized stinging cells are characteristic of Cnidaria, and what capsule inside them contains a coiled thread used to capture prey?

Cnidocytes, which contain a nematocyst

What are the major body plan traits of phylum Cnidaria regarding symmetry, tissue layers, and body cavity?

Radial symmetry, diploblastic (two germ layers), and no body cavity