Post on 31-Mar-2015
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Evolution & MorphologyGeneral Zoology, 18 January 2008
Donald Winslow
Readings from Hickman et al. 2008:
Ch. 6 pp 105-113, 115-130, 132-134
Ch. 9 pp 186-190, 192-194
Founders of evolution• Lamarck—inheritance of acquired traits
• Lyell—uniformitarianism & gradualism
• Malthus—exponential growth & limitation
• Darwin—natural selection, speciation
• Wallace—independently developed
theory of evolution by natural selection
& inspired Darwin to publish.
Charles Darwin• Voyage on H.M.S. Beagle, Galapagos
• Natural selection & adaptation– Population growth & limits to growth– Competition and heritable variation– Differential survival & reproduction– Gradual adaptation & speciation
• Reproductive barriers & speciation
Evidence for evolution• Fossil record
– Marine organisms on mountaintops
• Geological time & dating—isotope decay
• Evolutionary trends—horses
• Homology of vertebrate forelimbs (Fig 6.14)
• “Ontogeny recapitulates phylogeny.”– Haeckel
Flying Great Egret (Ardea alba). Photo by Karen Bays.
Bird wings are homologous to a human’s arms.
Ontogeny & phylogeny
• Pharyngeal gill slits
• Paedomorphosis
• Heterochrony
Microevolution
• Population genetics
• Gene pool
• Allele frequencies
• Hardy-Weinberg equilibrium
Forces that change allele frequencies
• Mutation
• Genetic drift
• Nonrandom mating—e.g. assortative mating
• Migration
• Selection (natural, artificial, sexual)– Relative fitness– Stabilizing, directional, & disrupting selection
Bright plumage of male Northern Cardinal—
A result of sexual selection.
Measuring genetic variation
• Protein polymorphism & heterozygosity
• Gel electrophoresis
• Quantitative characters
Dark-eyed Junco (Junco hyemalis) color variants
Macroevolution
• Allopatric & sympatric speciation
• Hybridization, extinction
• Adaptive radiation (diversification)
• Gradualism, punctuated equilibrium
• Mass extinction
• Levels of selection– Genic, individual, kin, group, species
Morphology
• Biological hierarchy
• Grades of organization & body plans
• Describing locations on animal bodies
• Body cavities & germ layers
• Developmental patterns
• Histology
• Body size
Biological hierarchy
• Cell
• Tissue
• Organ
• Organ system
• Organism
• Population
• Community
Nine-banded armadillo
Grades of organization
• Protoplasmic (e.g. protozoa)
• Cellular (e.g. colonial protists, sponges)
• Tissue (e.g. jellyfish)
• Organ (e.g. flatworm)
• Organ system (e.g. molluscs, arthropods)
Luna
moth
Body plans
• Unicellular protists vs multicellular animals– Protozoa vs Metazoa
• Cell-level vs tissue-level organization– Porifera vs Eumetazoa
• Radial symmetry vs bilateral symmetry
• Sac vs “tube-within-a-tube” digestive tracts
• Acoelomate, pseudocoelomate, coelomate
Describing location on animal
• Anterior/posterior
• Dorsal/ventral
• Medial/lateral
• Distal/proximal
• Frontal, sagittal, and transverse planes
Body cavities
• Blastocoel
• Gastrocoel (archenteron)
• Pseudocoel
• Coelom
Germ layers
• Endoderm
• Mesoderm
• Ectoderm
Developmental patterns
• Cleavage—radial or spiral
• Gastrulation (germ layer formation)
• Diploblastic or triploblastic
• Protostome or deuterostome
• Metamerism (segmentation)
Histology
• Blood plasma and interstitial fluids
• Tissues• Endoderm epithelium of digestive tract
• Ectoderm skin & nervous tissue
• Mesodermconnective tissue, muscles, viscera– Connective tissue:
» collagen, blood, lymph, cartilage, bone, fat
Advantages & disadvantagesof large body size
• Predators can subdue larger prey,
• But larger prey can’t hide as easily.
• Larger animals have efficient metabolism,
• But use more energy.
• Larger animals have longer generations.
Humpback whale