Unit 1 Evolution and Change

Andrew ShawAP Biology 5th

Adaptive Radiation

adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage.

Allometric Growth

the variation in the relative rates of growth of various parts of the body, which helps shape the organism

Allopatric Specification

a mode of speciation induced when an ancestral population becomes segregated by a geographic barrier or is itself divided into two or more geographically isolated subpopulations

Allopolyploid

a common type of polyploidy species resulting from two different species interbreeding and combining their chromosomes

Artificial selection

the selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits

Autopolyploid

an individual that has more than 2 chromosome sets, all derived from a single species

Biogeography

the study of the past and present distribution of species

Bottleneck Effect

genetic drift resulting from the reduction of a population such that the surviving population is no longer genetically representative of the original population

Cline

clines consist of ecotypes or forms of species that exhibit gradual phenotypic and/or genetic differences over a geographical area

Convergent Evolution

species evolve to have structures with similar functions due to similar environments

Diploidy

presence of 2 copies of each chromosome in a cell

Directional Selection

natural selection that favors individuals at one end of the phenotypic range

Diversifying Selection

Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values.

Founder Effect

genetic drift that occurs when a few individuals become isolated from a larger population with the result that the new population's gene pool is not reflective of the original population

Frequency-dependent Selection

a decline in the reproductive success of a morph resulting from the morph's phenotype becoming too common in a population; a cause of balanced polymorphism in populations

Gametic Isolation

If the gametes of two species meet, fertilization may not occur because of gametic isolation, in which the egg and sperm of different species are incompatible.

In coral reefs, gamete incompatibility prevents the formation of numerous inter-species hybrids.

Genetic Drift

unpredictable fluctuations in allele frequencies from one generation to the next because of a population's finite size

Gradualism

gradualism is a theory which holds that profound change is the cumulative product of slow but continuous processes

Heterochrony

developmental change in the timing of events, leading to changes in size and shape

Heterozygote Advantage

greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools

Homeotic

any of the genes that control the overall body plan of animals and plants by controlling the developmental fate of groups of cells

Homologous Structures

the same organ in different animals under every variety of form and function

Hybrid Breakdown

In plants more than in animals, hybrids between closely related species are sometimes partially fertile. Gene exchange may nevertheless be inhibited because the offspring are poorly viable or sterile.

Natural Selection

is the nonrandom process by which biologic traits become more or less common in a population as a function of differential reproduction of their bearers

In a lighter environment natural selection favors lighter moths leading to an increase in populations of white moths and a decrease in black moths

Neutral Variation

hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection

you don't live or die or reproduce more or less according to your eye color.

Paedomorphosis

retention in an adult organism of the juvenile features of its evolutionary ancestors

Polymorphism

Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species-Dark-morph or melanistic Jaguar (about 6% of the South American population)-Light-morph Jaguar (typical)

Polyploid

organism has more than 2 complete chromosome sets

Postzygotic Barriers

the inability of the fetus or the zygote to survive once the eggs have been fertilized

Prezygotic Barriers

Barriers that take effect before fertilization

Punctuated Equilibrium

evolution occurs in rapid bursts

Reduced Hybrid Viability

The hybrid is very fragile. The genes of the different parents will interact and impair the hybrids development.

A specific subspecies of salamander live in areas where they occasionally meet and breed. Often times the offspring do not develop fully and those that do are not very fit.

Reduced Hybrid Fertility

The hybrids will survive and live a full life but they are unable to produce offspring

Ligers are infertile

Relative Fitness

describes the ability to both survive and reproduce, and is equal to the average contribution to the gene pool of the next generation that is made by an average individual of the specified genotype or phenotype

The Snowshoe hare is more fit than an animal that lives in the same environment but is less camouflaged

Sexual Dimorphism

polymorphism based on distinction between the secondary sex characteristics of males and females

Stabilizing Selection

natural selection favors those at the peak of the bell curve

Sympatric Speciation

speciation occurring as a result of a radical change in the genome of a subpopulation, reproductively isolating the subpopulation from the parent population

Temporal Isolation

species reproduce at different times

Wood Frog

Leopard Frog

Uniformitarianism

Lyell's idea that geologic processes have not changed throughout Earth's history

A photograph shows the current scene (2003), below John Clerk of Eldin's illustration of 1787.

Vestigial Organs

structure of marginal importance to an organism, remnants of structures that had important functions in its ancestors