Genetics 6: Conservation, Evolutionary, and Ecological Genetics

Effective reproduction number

Number of breeding animals in a theoretical population that would embody the entirety of the genetic diversity in the actual population

1. Always less than the actual population size

   1. Reflects genetic diversity: lower N_e = less diversity

   2. Non-biologic example: cars

Inbreeding

1. Low N_e = higher average relatedness between individuals → ___

   1. Decreased fertility

   2. Decreased viability of offspring

   3. Increased incidence of recessive disorders

2. Can remain a problem even if actual population size rebounds

   1. Population bottleneck

Bottleneck

Severely reduces population size and genetic diversity

Formulate mating strategies to maximize genetic diversity, sexing in ovo embryos to help manage sex-skewed populations, identify species differences in phenotypically-similar populations

How can genetics tools aid conservation?

Non-invasive DNA analyses

1.  Eliminate the need to capture and handle individuals

   1. Feces, hair, feathers, saliva, shed skin

2. DNA subsequently used for mitochondrial and nuclear DNA sequencing, microsatellite analysis, sex identification, and pathogen diagnosis

   1. Can often identify individuals from only a few markers– once known, a sample can be assigned to an individual even if they were not observed

3. Accurate population count, data on each individual’s sex, mating patterns, and relatedness to others in the group

   1. Helps identify appropriate conservation and management units → what species/subspecies exist that need to be preserved, and how unique are they?

Convergent evolution

1. Development of similar traits in organisms that are not closely related

2. Traits arose after split from common ancestor

3. Adaptive response to similar environments or ecological niches

Tenets of evolutionary genetics

1. Variation continuously arises in a population via mutation and recombination.

2. Populations evolve by changes in gene frequencies through

   1. Genetic drift

   2. Gene flow

   3. Natural selection

3. Most adaptive variants have minor effects; thus, phenotypic change is gradual

4. Speciation most often occurs through reproductive isolation

5. These processes, continued for a sufficiently long period, produce changes sufficient to delineate higher taxonomic levels (genus, clade, etc.)

Genetic drift

Changes in allele frequency within a population over time that are due to chance

Gene flow

Movement of alleles between populations

Local adaptation

Population will have higher fitness at its native site than any other population introduced to that site

Phenotypic and genetic differences along environmental gradients or between contrasting habitats

What is indicative of local adaptation?

Speciation

Adaptation to ecological niches leads to ___.

Species

Group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding

Hybrids

1. Result of mating between two animals of different breeds, varieties, species, or genera

   1. May or may not be reproductively viable

      1. ___ that can reproduce may become their own species or sub-species

Variation

Gene flow can constrain speciation and help maintain ___.