chapter 11 biology

what are the preserved remains, or traces of remains, of ancient organisms. Ex. Molds, casts, imprints, and remains

fossils

process of determining age of remains based on content and decay rate of radioactive isotopes

absolute dating

widely distributed fossil, of narrow range in time, regarded as characteristic of a given geological formation

index fossil

in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom

law of superposition

 process of determining age of remains based on position in rock strata

relative dating

 structurally similar features in different organisms suggesting common ancestry, structures perform different functions

homologous structures

what type of evolution do homologous structures suggest

divergent evolution

 similar features found in unrelated organisms that have evolved to perform the same function

analogous structures

what evolution is suggested in analogous structures

convergent evolution

an anatomical feature that no longer seems to have a purpose in the current form of an organism; ex. Blind fish and salamanders who live in caves still have eye structures

vestigial structures

 the study of the similarities and differences in the development of embryos of different species

comparative embryology

presented one of the first theories of evolution in 1809

believed that evolutionary changes were caused by organisms actively adapting themselves to environmental conditions

Lamarck

the more an animal uses a particular structure the more prominent and well-developed the structure will become.  The less a structure is used the less prominent and well-developed it will become.

the law of use and disuse

what are Three Major Points of Darwin’s Theory of Descent with Modification through Natural Selection

species overproduce, competition for limited resources will occur, due to variation among individuals some will be better at competing for limited resoruces

favorable genetic variation; makes an organism more likely to survive and reproduce

adaptation

measure of reproductive success; how many surviving offspring are produced

fitness

accumulation of favorable adaptations over time which result in the formation of a new species

speciation

condition in which allele frequencies in a population do not change from one generation the next; rate of occurrence of traits remains constant; no evolution occuring

genetic equilibrium

extreme phenotype becomes a favorable adaptation; usually caused by change to environment or migration to new habitats

directional selection

average phenotypes become more favorable and extreme phenotypes become more unfavorable; usually inhibits the rate of evolution because of a narrowed range of variation

stabilizing selection

rare form of natural selection; extreme phenotypes become more ,favorable than average phenotypes, creates two separate subpopulation

disruptive selection

term used to describe how often a particular allele occurs in a population

allelic frequency

all of the possible alleles that exist in a population

gene pool

what are the conditions necessary to maintain genetic equilibrium ?

no mutations, nobody can enter or leave population, have a large population, mate randomly/no selective breeding, no natural selection

movement of genes from one population to another

gene flow

a change in the allelic frequency of a small population brought about by chance; two important causes of this are Founders/Bottleneck Effect:

genetic drift

 populations started by a few pioneering individuals moving into a new region (reduces genetic variation)

founders effect

a small group of surviving members of a population breeding together (reduces genetic variation)

bottleneck effect

new land or water barriers form; examples include change in the course of a river or new highway built across a field

geographic isolation

species arise in separate settings

allopatric speciation

inability of formerly interbreeding organisms to mate and produce fertile offspring

reproductive isolation

species arise in the same setting

sympatric speciation

species evolve adaptations that prevent mating

prezygotic

 though species interbreed, mating is unsuccessful

postzygotic

joint change in two or more species in close interaction i.e. predators/prey or plants/pollinators

coevolution

unrelated species become more and more alike (evidence = analogous structures) in appearance as they adapt to similar environmental pressures

convergent evolution

 process by which two related species become more dissimilar ( evidence = homologous structures) over time as they adapt to separate environments

divergent evolution