Chapter 22-23 Vocab

represent variations on a structural theme that was present in their common ancestor; show evidence of relatedness. (arms, forelegs, flippers, and wings)

remnants of features that served a function in the organisms ancestors. (ex. tailbone - coccyx)

similar solutions to similar problems but do not indicate close relatedness. (bird wing, butterfly wing)

the independent evolution of similar features in different lineages; analogy; usually the result of evolution to similar environments

the scientific study of the geographic distributions of species

1 homology

2 fossils

3 biogeography

4 drug resistant bacteria

when an increase in one trait, feature, or behavior results in a simultaneous decrease or cost in anothe

1 natural and sexual selection

2 genetic drift

3 gene flow

4 mutation

females choose while males compete

occurs when individuals/gametes move from one population to another (can lead to reduced fitness in some populations)

change in allele frequency due to chance; describes how allele frequencies fluctuate randomly from one generation to the next

a permanent change in the DNA or RNA sequence of an organism or virus

1 formation of new alleles (genes); mutation

2 altering gene # or location; chromosomal mutations

3 rapid reproduction; mutation rates constant

4 sexual reproduction; recombination of chromosomes

external expression of a genotype

an individual's unique set of genetic instructions, or the specific sequence of DNA inherited from parents

occurs when few individuals start new population in new area; founder population usually smaller than source population; disproportionate effect of genetic drift

a sharp, sudden reduction in the size of a population caused by environmental disasters or human activities usually caused by traumatic event and severely decreases genetic diversity

1 directional

2 stabilizing

3 disruptive

increases frequency of allele, reduces genetic diversity, favored alleles become fixed

frequency of 1.0/100, disadvantageous alleles decline in frequency.

changes the average value of a trait (favors one extreme characteristic)

intermediate traits reproduce more than others, reduces population's genetic diversity over time, no change in average value of trait over time

reduces variation (favors the average trait)

intermediate phenotypes selected against, extreme phenotypes, maintains genetic diversity, can cause speciation

increases the amount of variation (favors the most fit and least fit)

traits differing between males/females of the same species; often differ sharply

a lineage-splitting event that produces two or more separate species; occurs when population is split and they live in different geographic locations

formation of a new species if individuals with one extreme of trait start mating preferentially with those that have the same trait

an organisms reproductive cells; sex cells

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome; specific variation (blue or brown eye color)

the basic physical and functional unit of heredity, made up of a specific sequence of DNA that provides instructions for building proteins; general section (eye color)

evolutionarily independent population or group of populations

impede mating or prevent fertilization if mating does not occur

habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation

result in fetal death and/or infertile offspring

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

geographic; a population forms a new species while geographically isolated from its parent population

no separation; a subset of a population forms a new species without geographic separation

no physical barrier preventing gene flow, isolation based on habitat preferences

occurs when populations are separated (river/mountain range/etc., when individuals cannot cross a barrier, leads to no gene flow)

duplication of chromosomes; usually from multiple closely related species

reinforcement

fusion

stability

strengethen reproductive barriers

breakdown of reproductive barriers

continued reproduction of hybrids

a collection of behaviors, physiological processes, and genetic traits that stop members of different species from producing viable, fertile offspring

when two species or populations living in the same geographic region occupy different specific habitats, preventing them from meeting and mating

an evolutionary mechanism when two populations or species prevent interbreeding by reproducing at different times, such as different hours of the day, seasons, or years.

prezygotic barrier where differences in courtship rituals, mating calls, or signals prevent closely related populations or species from interbreeding.

a physical difference in reproductive structures that stops different species from mating

when the sperm and egg cells of different species are chemically or molecularly incompatible, preventing them from fusing into a zygote

when hybrid offspring resulting from the mating of two different species have a lower chance of surviving to maturity

when offspring resulting from the mating of two different species survive to adulthood but are sterile or have low capacity to reproduce

when the first-generation (F₁) hybrid of two species or subspecies is healthy and fertile, but the subsequent generation (F₂) or backcross offspring suffer from reduced fitness, sterility, or death.