Adaptation Flashcards
Define adaption:
A change or the process of change by which an organism or species becomes better suited to its environment
Who emphasised on the role of inheritance in explains the similarities between organisms?
Lamark and Darwin
What did Lamark and Darwin argue?
Modification were gradual and not random but arose in response to an organisms environment
What are the foundations of natural selection?
- Some individuals are fitter, better suited to the environment
- Survive and produce more offspring than less fit individuals
- Frequency of genes encoding such traits increas
Define Muller’s ratchet:
Accumulation of deleterious mutations (which can be removed by sexual reproduction & recombination)
What may the population look like if the rate of mutation or drift balances selective pressure
Is not under pressure
What does the fundamental niche of species include?
- Total range of environmental conditions that are suitable for living
- No influence of interspecific completion or predation from other speices
What is a resized niche?
Part of the fundamental niche actually occupied by species
What promotes adaptation?
- Moderate mutation rates
- A small amount of gene flow
- Directional selection
- Developmental competence
What prevents adaptation?
- Inbreeding
- Genetic drift
- Large amounts of gene flow
- Stabilizing selection
Fill in the the gap;
Smaller popluaino gave less potential for…than larger populations
local population
What will wide spread populations experience?
Different environnemental conditions
What will wide spread populations consist of?
Number of sub-populations that differ slightly or with consideraly
What is body plan?
Common basic body plan for different groups of organisms
Give an example of the body plan:
The eye - contains similar structures in many mammals but do different slightly
What can adaptation lead to?
Wide spread changes in development patterns leading to macroevolutionary events
What is saltation?
Major changing events
What is the 2 main debates in evolutionary biology concerning speech of evolutionary change?
- Gradualism
- Punctuated-equlibrium
What is gradualism?
Evolution generally occurs uniformly and by the steady and gradual transformation
What is punctuated-equilibrium?
Evolution is marked by isolated episodes of rapid speciation between long periods of little or no change
What are homologous structures?
Extant species allow us to infer functions in (related) extinct species
What is analogous structures?
Unrelated species where no common descent mean that great care must be taken in establishing functions of traits in extinct species
Give 3 categories that must be fitted to be homologous structures:
Similarity by common descent,
similar form and function,
similar developmental trajectory
Give 3 categories that must be fitted to be analogous structures:
Different ancestry,
same function,
different developmental trajectory
Define exaltation:
Adaptation that involves new uses for existing traits
Define linked traits:
Traits may be selected ‘for’ because they are linked to something else
When does linked traits occur?
Allele changes frequency not because it itself is under natural selection, but because it is near another gene that is undergoing selection
What is the Pangloss’s Optimism?
Everything happens out of absolute necessity, and that everything happens for the best
Is Dr Pangloss correct that all adaption are for the best?
No, male genitals is not efficient
What is Dollo’s law?
Evolution is not reversible; i.e., structures or functions discarded during the course of evolution do not reappear in a given line of organisms.
What doe adaptationists seek to find?
Adaptive explanations for every characteristic of an organism, however
What nonadaptive?
selectively neutral
What is male urogenital system about adaption?
- Once a pathway of successive adaptations begins, reversals may be competitively disadvantageous or difficult to achieve
- Ancestry apparently constrains the range of variation available to natural selection
What is an example of nonadaptive?
Maladaption
What is the point of maladaptive?
Not adaptive just maintains the adaptions in the population
Why must we be wary of function of adaptions?
-People can make up the function of the apaption
Define co-evolution adaptation:
The evolution of reciprocal adaptations of two or more species that have prolonged close interactions
What is co-evolution expected in?
Mutualism (++)
Parasitism, predation (-+)
Competition (–)
What is co-evolution not expected in?
Commensalism (o+)
Amensalism (-o)
What is the red-queen hypothesis?
- The biotic and abiotic world is constantly changing, shifting adaptive peaks
- Each species in an ecosystem is engaged in a permanent race with others
- Success for one inevitably means a decline for another
What is an arms race related to adaptation?
Situations where an innovation one species leads to a counter innovation in the other
What are mullerian mimics?
Two species mimic each other
Which species are usually the models since it what the selective agents are cuing on in regards to mullerian mimics?
Abundant species
Why is co-evolution a two step process?
- major gene mutation to make the less protected species look more like protected species
- Then minor gene mutation in both species that refine mimicry
What is batsman mimicry?
- one unpalatable species
- May not involve co-evolutionary phenomena
Define adaptive radiation:
The spread of new species of common ancestry into different niches, involving an excess of cladogenesis over extinction
Define convergent evolution:
Organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches
Do homologous structures evidence of convergent evolution or adaptive radiation?
Adaptive radiation
Do analogous structures evidence of convergent evolution or adaptive radiation?
convergent evolution
What permits the coexistence of multiple species?
Diversification into different ecological roles, or niches
What promotes adaptive radiation?
- Intrinsic factors (metabolic and physiological and development opportunities )
- Efficient dispersal
- Extrinsic factors (empty habitats/novel environments/intensity of selection/founder effects)
- Ecological releases
What is ecological releases?
Occurs when a species expands its niche within its own habitat or into a new habitat where there is little competition for resources, which remain abundant
What are the three stages on adaptive radiation?
- Divergence of linage into different major habitats
- Morphological specialisation leading to trophic differentiation within habitats
- Sensory communication diversification (sexual selection)
An example of convergent evolution:
Marsupial mammals to Eutherian mammals
What is molecular convergent evolution?
Independent episodes of molecular evolution occurred, with the same functional results.
What is an example of molecular convergent evolution?
Antarctic fish vs Arctic fish
What are the limitations of convergent evolution?
- Contingency
- Functional/physical constraints
- Developmental constraints
- Genetic constraints
What is contingency?
Evolution is based on chance events and/or dependent on other chance events
Criteria for adaptive radiation:
- common ancestry
- phenotype – environment correlation
- trait utility
- rapid speciation
- key evolutionary innovation and rapid diversification
What is adpationist programme?
Seeks to find adaptive explanations for all traits in biology and has been a major concern of evolutionary biologists
What is adaption described in terms of?
Their ability to promote fitness
Wha are two experimental approaches to adaptation?
- Manipulate species
- Manipulate environment
How do manipulate species?
- Population size
- Variation (sexual vs asexual, in-breeding / outbreeding)
- Attributes, e.g. size, colour
- Modify e.g. biomimetics (tail, wing)
How do you manipulate environment?
- Modify species composition
- Exclude or add predators / hosts
- Alter physical factors e.g. temperature, humidity etc…
What type of experiments are adaptation experiments?
Replicate and reproduce experiments
Why are microbes a good model for experiments?
- Easily propagated
- Rapid generation times
- Large population sizes
- Easily stored (compare ancestors)
- Environment readily controlled
- Asexual or sexual
- Single or mixed genotype
- Phenotypes are easily detected
- Whole genome sequencing
Direct genetic manipulations possible
When are microbes not a good model for experiments?
For complex animals and humans
What were the stated aims in Ralney and Travisano?
Examine role of ecological opportunity and competition in driving genetic diversification
What were the conclusions in Ralney and Travisano?
- Ecological opportunities promote morphological diversification
- Ecological homogeneity does not promote divergence
- Mutation and selection alone are sufficient to promote new designs
- Competition amongst niche variants maintains variation
- Trade-offs in competitive ability drive adaptive radiation
What do ecological opportunities promote?
Morphological diversification
What is required to maintain diversity?
Spatial heterogeneity
What is human induced selection?
Humans having an extreme effect on environment
The rate of evolution is much faster than once thought
What is urban selection?
Novel ecosystem: with increase noise and light pollution adaptation, new diets, altered hydrology and surface cover
What does isolate environments implicate?
- Migration
- Bottlenecks
What does change in climate have to do with adaption?
Adaptation to warming temperatures, changes in precipitation, change in frequency and severity of extreme events
What prevents adaption?
- Inbreeding
- Genetic drift
- Large amounts of gene flow
- Stabilizing selection
