Population growth and regulation — in a stable population inputs (natality and growth) are

1. Population growth and regulation — in a stable population inputs (natality and growth) are balanced by outputs (harvest and natural mortality) —if inputs are higher then population grows, if outputs are higher then population declines — only a certain biomass can be supported by a particular area; some limiting factor (food, shelter, water, etc.) will stop population growth — sometimes species in new environment will increase at an exponential rate, J-curve; this can only continue as long as no limiting factors are reached — when this happens the growth curve flattens to an S-curve or logistic growth curve

3. — this happens at carrying capacity (k), the max biomass of • a population that can be sustained within a defined area for • a given amount of time • — inflection point is where population starts increasing at a • decreasing rate • — managers may consider k to be at a level where the • population does not severely damage the habitat; • management practices can change k for a pop in a given • area by improving habitat • Examples: • increasing cover and food for quail to increase • removing roosting habitat for blackbirds to decrease • — biotic potential - max rate of population increase under • ideal conditions

4. — environmental resistance - biotic and abiotic factors that limit population growth; includes predators, food, water, nesting sites, similar competitors, etc. —combination of biotic potential (increases #) and resistance (decreases #) is ultimately what sets k — many times we see a cyclic pattern; environmental factors change and this effects population size Example: as the population increases the habitat is degraded and fewer individuals can be supported so #’s drop; as #’s drop, the habitat improves and can support more individuals so k and #’s goes up Production and yield — production - biomass, living and dead, accumulated by a population during a year

5. — surplus production - portion that can be removed from population by natural causes or harvest w/out adversely affecting future populations; part we take is yield — we try for maximum sustained yield (MSY) – we consider ecological and socioeconomic factors when deciding where to hold a population; usually between inflection point and k Ecological: – population size that is not harmful for target species with regard to disease, body condition, sustained yield – must not overload habitat and degrade it for future animals (overgrazing or overbrowsing) Socioeconomic: – How many animals do the public want to see? – Do they want trophy size animals? – Is the population causing undue risk and/or cost to the public? traffic accidents, agricultural damage/economic loss

6. Genetics – genes - segments of hereditary material that are positions on chromosomes – chromosomes - structures that carry genes and are in the nuclei of every cell of an organism – most vertebrates are diploid - have 2 sets of chromosomes that are paired; get one copy from mother and one from father; each copy has every gene and known as alleles; humans get 23 chromosomes from each parent (46 total) – alleles occur on the same area, called a locus, of the chromosome and there may be alternative forms of the same gene; we get one allele from each parent – genotype – all genetic information possessed by individual

8. –phenotype - actual physical expression of traits; genotype reacting with environment; you can have same genotype and 2 phenotypes or vice versa – individuals with 2 copies of the same allele is homozygous and those with 2 different alleles are heterozygous – can have dominant and recessive alleles; dominants are expressed over recessives – can have incomplete dominance where one allele is expressed a little more over another or co-dominance where both are expressed equally – gene pool of a population - all the alleles present within all the individuals in the population

10. – in general, the less diverse the gene pool the less a population will be able to adapt to changing environmental conditions; variety is better – evolution - changes in the gene pool over time that lead to adaptation to the environment; products of evolution are geneticallynew organisms