TOPIC 4: Biodiversity Flashcards
What is a species?
a group of closely related organisms with similar morphology, physiology and behaviour, which can interbreed to produce fertile, viable offspring.
What problems are there with defining species?
asexual, extinct, rare, geographically isolated
Define niche
the way an organism uses its environment & it’s role in the environment/ecosystem (predator? prey?)
What happens when two species occupy the same niche?
two species cannot occupy the same niche so there’s either splitting of the niche (one adapts to other niches) or extinction of one of the species.
What is fundamental niche?
the largest niche an organism could occupy without competition
What is realised niche?
the niche actually occupied due to competition
Define ecosystem
A self-sustaining life-supporting environment with biotic and abiotic factors
Define community
All the populations of different species sharing an ecosystem
Define population
total number of individual species within a community
What is an adaptation?
behavioural, physiological & anatomical features of an organism that help it survive in its habitat
What’s a physiological adaptation?
features of cells, tissues & systems to help an organism survive in its habitat
What’s a behavioural adaptation?
actions by organisms that help an organism survive in its habitat
What’s an anatomical adaptation?
visible, physical features that help an organism survive in its habitat
What’s co-adaptation?
adaptation of 2 or more organisms resulting in mutual benefit
What is directional selection?
selection pressure favoring one extreme trait, against the other
What is stabilising selection?
favoring mean, selecting against both extremes
What is disruptive selection?
favours both extremes, against mean
bimodal distribution
What causes allele frequencies to change?
genetic drift, non-random mating, natural selection, migration/emigration, mutations
What is genetic drift?
change in allele frequency due to chance (bottleneck - natural disaster/disease)
How does speciation happen?
- some individuals migrate to nearby islands & are geographically isolated;
different mutations and selection pressures; - species adapt to each region for survival & breeding;
- change in allele frequencies over time & difference between gene pools;
REPRODUCTIVE ISOLATION due to restricted gene flow
What is meant by populations adapting?
change in allele frequency in population
What factors increase the ability of a population to adapt?
strong selection pressure,
fast reproductive rate,
large gene pool
Why is it unlikely a population can be perfectly adapted to their environment?
environments change; time lag to adapt,
selection pressure is always present,
mutations (new alleles)
Why might it be a problem to be perfectly adapted?
dependence on other species makes them vulnerable if they die out,
less likely to survive environmental changes
