Population and Communities Flashcards
(16 cards)
What is population growth dependent on?
-Immigration - movement of Individuals into the population.
-Emigration - movement of individuals out of the population.
-Natality - births
-mortality- death
What is primary succession?
-Begins when there is no soil present. (E.g newly formed island).
-Pioneer species: first species to colonize an area. Small and opportunistic species, grow in harsh conditions. (Lichen).
-As the organisms die soil is formed, allows for larger species such as grass to grow.
-Animals eventually join the. Community following the same pattern.
-Climax community: community which remains fairly stable if there are no environmental changes.
What is secondary succession?
-The recolonization of an area after ecological disturbance (fire, flood, etc).
-Soil is still present.
What is Intraspecific competition?
-Competition for limited resources between members of the same species. (Same school).
What is interspecific competition?
-Competition for limited resources among members of two or more populations.
What are the agents of evolutionary change?
- Mutations: Change in DNA of an individual.
- Gene flow: net movement of alleles from one population to another (due to migration of individuals).
- Non-random mating (sexual selection): preventing individuals with certain phenotypes from mating.
- Genetic drift: due to small populations (change in allele frequencies due to change events).
- Natural selection: when a mutation produces a phenotype.
What is the founder effect?
-The gene pool change that occurs when a few individuals start a new, isolated population.
-Founders carry some but not all of the alleles in the original population.
What is the bottleneck effect?
-The gene pool change that results from a rapid decrease in population size.
-Caused by starvation, disease, human activities or natural disasters.
-Significant changes to the gene pool over time results in evolution or speciation.
What are the conditions for Hardy Weinberg?
-Populations will remain the same from generation to the next as long as:
1. Large population
2. Random mating
3. No net mutations
4. No migration
5. No natural selection (for/against any phenotype)
What are Mendel’s Law of Heredity?
- Inherited characteristics: are controlled by genes that occurs in pairs. During cross-fertilization each parent contributes one of its genes.
- Law of dominance: one factor or gene masks the effect of another.
- Law of segregation: A pair of genes, separate or segregated during the formation of sex cells.
- Law of independent assortment: two alleles for one gene separate independently of the allies for other genes during gamete formation. (Coin flip).
What are parental and recombinant types?
Parental types: individuals with chromosomes (phenotypes) identical to the parents.
Recombinant types: individuals with chromosomes different than the parents.
What are continuous and polygenic traits?
Continuous traits: traits for which phenotypes vary gradually from one extreme to another. E.g height.
Polygenic traits: traits that are controlled by multiple genes. E.g skin color. (Dominant alleles contribute to the trait and recessive does not).
What is succession?
-The sequence of invasion and replacement of species in an ecosystem over time.
What is r-selected?
-Species that reproduce close to their biotic potential.
-Short life span
-Early reproductive age
-Large number of offspring
-Little to no parental care
-Small body size
-E.g insects or bacteria
What is K-selected?
-Populations that live close to their carrying potential.
-small number of offspring
-more extensive parental care
-large bodies
-long lives
-e.g bison or hawks
What is carrying capacity?
-Maximum number of individuals in a population that an environment can support without significant negative impacts.
