Unit 2:Organisms and evolution KA2.2-evolution Flashcards
define the term evolution
evolution is the change over time of the proportion of individuals in a population differing in one or more traits
what can cause evolution to be rapid
selection pressures
name the 2 types of selection pressures
biotic and abiotic
name some biotic factors
competition, predation, parasitism and disease
name some abiotic features
changes in temperature, light, humidity, pH and salinity
what are the 2 types of evolution
random and non-random
example of random evolution
genetic drift, examples of this is population bottleneck and the founder effect
types of non random selection
natural selection and sexual selection
why does variation exist in a species
mutations
description of male-male rivalry
large size or weaponry increases access to females through conflict
description of female voice
female choice involves females assessing the fitness of males
define genetic drift
the ratio of genotype change randomly overtime and can result in some alleles being under or over represented
describe population bottleneck
a population bottleneck is an event that drastically reduced the size of a population for at least one generation, leaving a population with a reduced genetic diversity
describe the founder effect
founder effect occurs through the isolation of a few members of a population from a larger population
this new gene pool is not representative of the original one
the 5 conditions for maintaining the hardy-weinberg principle
-no selection occurring
-no mutation
-no migration
-random mating
-large population
define the term fitness
fitness is a measure of the tendency of some organisms to produce more surviving offspring than competing members of the same species
fitness can be describes in absolute or relative terms
what does p mean in the hardy weinberg equation
frequency of the dominant allele
what does q mean in the hardy weinberg equation
frequency of the recessive allele
what does p squared mean in the hardy weinberg equation
frequency of the homozygous dominant genotype
what does 2pq mean in the hardy weinberg equation
frequency of the heterozygous genotype
what does q squared mean in the hardy weinberg equation
frequency of the homozygous recessive genotype
what are the hardy weinberg equations
p+q=1
p squared + 2pq + q squared=1
what is absolute fitness
the ratio of frequencies of a particular genotype from one generation to the next
what is relative fitness
the ratio of surviving offspring of one genotype compared to other genotypes
define the term co-evolution
the process by which 2 or more species evolve in response to selection pressures imposed by each other.
A change in the traits of one species acts acts as a selection pressures imposed on the other
definition of mutualism
-both organisms in the interaction are interdependent on each other for resources or other services
-both organisms gain something from the relationship
definition of commensalism
only one of the organisms benefits, but the interaction does not negatively affect the other
definition of parasitism
the parasite benefits in terms of energy or nutrients and the host is harmed as a result of the loss of these resources
define the term symbiosis
a co-evolved intimate relationship between members of 2 different species
