Class Introduction - Comparative Anatomy

constraints to design

geometry and relationship of length, surface area, and volume

larger animals have greater significance of ____

gravity

smaller animals have greater significance of _____

surface tension

even if shape remains the same, increases in _____ change the proportions among length, surface, and volume

size

which proportion increases the most when size changes?

relative surface area

what three things rely on relative surface area?

rate of oxygen uptake, diffusion of oxygen from blood to tissues, gain/loss of body heat

as body size increases, what decreases?

oxygen consumption per unit of body mass

three reasons to study comparative anatomy

evolution/phylogeny, zoology/classification, veterinary/animal science (husbandry)

homology definition

features with common ancestry

example of homologous features

bat and mouse arm

analogy definition

features with similar functions

example of analogous features

bat vs dragonfly wing

homoplasy definition

features that simply look alike

example of homoplastic features

orchid and orchid mantid

example of homologous, analogous, and homoplastic features

chimpanzee and gorilla hand

evolution

change through time

extremely theoretical aspect of evolution

biochemical origin of life

mostly theoretical aspect of evolution

all organisms derived from a single-celled organism

aspect of evolution in the middle of theoretical and proven fact

humans evolved from primates

aspect of evolution that is essentially proven fact

natural selection within a species

five evidences of evolution

the fossil record, biogeography, comparative anatomy, comparative embryology, molecular biology

how does the fossil record support evolution

shows enormous change through time, with simplest fossils at the deepest layers and complex fossils at the shallowest layers

critique of the fossil record as evidence for evolution

the Cambrian explosion - single-celled organisms in pre-Cambrian layer, Cambrian layer has marine animals

how do evolutionists explain the Cambrian explosion

punctuated equilibrium - all evolution occurred between pre-Cambrian and Cambrian layers

how does biogeography support evolution

organisms in the same area resemble each other, so one group of species must have evolved from the other

example of biogeographical evidence for evolution

South American vs Galapagos iguanas

how does comparative anatomy support evolution

anatomical similarities between species give signs of common descent from an ancestral species - homology

two aspects of comparative anatomy that support evolution

descent with modification, vestigial structures

how does comparative embryology support evolution

embryonic stages of many organisms are similar, appearances diverge only during later developmental stages

example of comparative embryology that supports evolution

all vertebrate embryos have pharyngeal slits and tails

how does molecular biology support evolution

at the biochemical level, every species is similar

two examples of molecular biology supporting evolution

every organism has DNA, codons are identical across species

how is evolutionary phylogeny largely determined today

by comparing DNA

two myths about evolution

we are evolving into higher beings, why are apes still around if humans evolved from them

debunk the “evolving into higher beings” myth

evolution is directionless, based solely on fitness which is based on the ability to pass genes on to the next generation

debunk the “if humans evolved from apes, why are apes still around?” myth

humans didn’t evolve from apes, just had a common ancestor and branched off