Ecology

Biology Unit 4, CH 22 and 23

Descent With Modification

the process by which species accumulate differences from their ancestors as they adapt to different environments over time.

Adaptations

Inherited characteristics of organisms that enhance their survival and reproduction in specific environments

Natural Selection

process in which individuals that certain inherited traits tend to survive and reproduce at higher rates than other individuals do BECAUSE OF those traits

Evolution

Definition: The process of species changing over time by genetic variation and natural selection.

Morphology

Study of the form and structure of organisms-shape, size, and arrangement of parts, analysis of both external features and internal structures -evolutionary relationships and functional adaptations of various species.

Population

a group of individuals of the same species that live in a specific area and can interbreed, producing fertile offspring.

Gene Flow

the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes.

Genetic Drift

Chance events that cause allele frequencies to fluctuate unpredictably from one generation to the next

Alleles

different versions of a gene arise by mutation and at the same place on a chromosome- Dif traits

Phenotype

observable physical or biochemical characteristics of an organism

Gene Pool

Consists of all copies of every type of allele at every locus in all members of the population.

Bottleneck Effect

A sudden change in the environment, such as a fire or flood, that drastically reduces the size of the population.

Founders Effect

When a few individuals become isolated from a larger population, this smaller group establishes a new pop whose gene pool differs from the source population

Homology

similarities resulting from common ancestry

Homologous Structures

Represent variations on a structural theme that was present in their common ancestor

Vestigial Structures

Remnants of features that served a function in the organism’s ancestor

Analogous Features

Features that share similar function, but not common ancestry.

Cladogram

aka. evolutionary tree. Diagram that reflects evolutionary relationships among groups of organisms.

Convergent Evolution

Independent evolution of similar features in different lineages.

Biogeography

The scientific study of the geographic distribution of species.

Microevolution

A change in allele frequencies in a population over generations

Genetic Variation

differences among individuals in the composition of their genes or other DNA sequences

Neutral Variation

Resulted by point mutations in non-coding regions. Differences in DNA sequences that do not confer a selective advantage or disadvantage

Hardy-Weinburg Equlibrium

For a population that is: not evolving, allele and genotype frequencies remain constant from generation to generation provided that only Mendelian segregation and recombination of alleles are at work.

Adaptive Evolution

Traits that enhance survival or reproduction tend to increase in frequency over time.

Relative Fitness

The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.

Directional Selection

when conditions favor individuals exhibiting one extreme of a phenotypic rate, thereby shifting a population’s frequency curve for the phenotypic character in one direction or the other.

Stabilizing Selection

acts against both extreme phenotypes and favors intermediate variants.

Sexual Selection

individuals with certain characteristics are more likely than other indiciduals of the same sex to obtain mates.

Sexual Dimorphism

A difference in secondary sexual characteristics between makes and females of the same species.

intrasexual selection

selection within the same sex, individuals of one sex compete directly for mates of the opposite sex.

intersexual selection

mate choice, individuals of one sex are choosy in electing their mates from the other sex.