Abac Ecology And Evolution Chapter 5

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Natural Selection

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Process by which traits enhancing survival and reproduction are passed on more frequently to future generations than those that do not

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What two conditions does Natural Selection produce?

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1) Variations occurs among individuals w/i a population in some heritable characteristic.

2) Variation results in differences among individuals in their survival and reproduction

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Evolution

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Process of natural selection results in changes in the properties of populations of organisms over the course of generations.

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Adaptation

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is any heritable behavioral morphological or physiological trait of an organism that has evolved over a period of time by the process of natural selection such that it maintains or increases the fitness of an organism under a given set of environmental conditions

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alleles

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The alternate forms of a gene

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Genome

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All of the DNA in a cell

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Dominant Allele

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The allele that is expressed masking the expression of other alleles

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Recessive Allele

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The allele that is masked

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Homozygous

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If the two copies of the gene are the same

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Heterozygous

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If the two copies of a gene are different

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Genotype

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The pair of alleles present at a given locus

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Phenotype

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The outward appearance of an organism for a given characteristic

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Co-dominant

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The physical expression of the heterozygous individual is intermediate b/t those of the homozygotes

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Qualitative Traits

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Phenotypic characteristics that fall into a limited number of discrete categories

Ex. Flower color

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Quantitative Traits

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Phenotypic characteristic that have a continuous distribution

Ex. Height, Weight

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What two reasons lead to Quantitative Traits?

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1) Most traits have more than one gene locus affecting them

2) most traits are affected by the environment

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Genetic Differentiation

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When genetic variation occurs among sub-populations of the same species

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Gene Pool

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The sum of genetic info. (alleles) across all individuals in the population

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Allele/Genotype Frequency

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The proportion of a given allele or genotype among all the alleles or genotypes present at the locus in the population

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Directional Selection

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A type of Natural Selection where the mean value of the trait is shifted toward on extreme over another

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Stabilizing Selection

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A type of Natural Selection where the favor individuals near the population mean at expense of the two extremes

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Disruptive Selection

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A type of Natural Selection where members of the population are subject to different selective pressures

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Mutation

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A heritable changes in a gene or a chromosme

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Migration

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the movement of individuals b/t local populations

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Gene Flow

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The movement of genes b/t populations

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Gene Drift

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Change in allele frequency due to random chance associated w/ sexual reproduction

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Assortative Mating

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when individual choose mates non-randomly w/ respect to their genotype - or more specifically, select mates based on the some phenotypic trait

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Positive Assortative Mating

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when mates are phenotypically more similar to each other than expected by chance

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Negative Assortative Mating

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when mates are phenotypically less similar to each other than expected by chance

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Inbeeding

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The mating of individual in the population that are more closely related than expected by random chance

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Inbreeding depression

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inbreed offspring are more like to inherit rare, recessive, deletrious genes. That cause decr. fertiligy, loss of vigor, reduced fitness, and even death

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Clines

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A measurable, gradual change over a geographic region in the average of some phenotypic character, such as size and coloration, or it can be a gradient in genotypic frequency

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Geographic isolates

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The free flow of genes among sub-populations is prevented by some extrinsic barrier

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Subspecies

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Geographic isolates that are exposed to different environmental pressures

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Ring Species

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A connected series of neighbouring populations, each of can interbreed w/ closely sited related populations, but for which the exist at least two "end" population in the series, which are two distantly related to interbreed, though there is a potential gene flow b/t each "linked" population

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Allopatric Speciation

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Speciation by geographic isolation, also reproductive isolation

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Sympatric Speciation

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Speciation by reproductive isolation w/i the same area.

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Reasons for Sympatric Speciation?

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Behavorial

Different habitat

Different Food Sources

Time of mating

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give two examples of Sympatric Speciation?

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Lake Victoria Cichlids

Three spine sticklebacks

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What are the two types of three spine sticklebacks?

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Limnetic sp.

Benthic sp.

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What Limnetic sp. Three spine stickleback feed on and in?

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open water and feed on plankton

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What Benthic sp.Three spine stickleback feed on and in?

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Sediments and submerged vegetation and feed on larger prey

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Adaptive Radiation

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The process in which one species gives rise to multiple species that exploit different featurews of the environment, such as food resources or habitats

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Phenotypic plasticity

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The ability of a genotype to give rise to different phenotypic expressions under different environmental conditons

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Developmental Plasticity

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Differences in phenotypic traits for a given genotype under different evironmental conditions reflect differences in the allocation of biomass to different tissues during the growth and development of the individual.

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Acclimation

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Reverible phenotypic changes in an individual organism in response to changing environmental conditions