Adaptation and Extinction Flashcards
When did the first animal evolve?
600 million years ago.
What were the earliest animals like?
Soft-bodied, marine suspension/detritus feeders.
What caused the Cambrian Explosion?
More oxygenated seas.
Break-up of Pannotia.
Increasing shallow sea area.
More potential niches.
What causes convergent evolution?
Similar selection pressures causing phenotypic convergence.
Why do taxa resemble each other?
Traits arose early.
Traits arose in the nearest common ancestor.
Traits arose by convergence.
Define adaptation.
The condition of organisms being well-equipped, both by structure and function or behaviour.
Define evolution.
A change in allele frequency in a population from one generation to the next.
Describe modern synthesis (neo-Darwinism).
The combined Mendelian theory of heredity and Darwin’s theory of evolution.
What is the molecular clock?
Molecular evolution occurs at almost a constant rate - mutation number can be used to determine divergence times.
Define genetic drift.
Allele frequencies changing randomly in a population from generation to generation.
Define niche construction theory.
A population changes its environment giving itself and other species an ecological inheritance with altered selection pressures.
What is Batesian mimicry?
An edible mimic deceiving predators by resembling a toxic model organism.
Define pre-adaptation.
A structure’s function changing considerably without much change in the structure itself.
Give an example of pre-adaptation.
Feathers in birds were used for insulation but were pre-adapted to act as aerofoils for flight.
How do we recognise adaptations?
Character fits too well to its environment.
Appearance of a complex design.
Character helps animal survive/reproduce.
What is an animal body plan?
An assemblage of morphological features shared among many members of a phylum level group.
Define tagmatisation.
The specialisation of body segments to perform a specific function.
Define convergent evolution.
The independent evolution of physiological or behavioural traits in organisms in different times or spaces.
What is synergism?
Multiple stressors acting together resulting in a combined effect great than the sum of their separate effects.
What are the 2 types of adaptation?
Animal’s action (behavioural) and physical.
What are vestigial structures?
Features that were adaptations for the organism’s ancestor but have evolved to be non-functional due to environmental change.
Define ecological development.
The influence of environmental factors on the expression of phenotypic traits.
How long does it take for the human gut microbiome to fully form?
3 years.
What host services does the gut microbiome provide?
Digestion of certain food compounds.
Production of bioactive molecules (vitamins).
Immune system stimulation.
Protection against pathogens.
Define an organism’s ecological niche.
The place or function of a given organism within its ecosystem.
When do organisms hibernate?
When reduced food availability coincides with low winter temperatures which increase metabolic energy demands.
What are the main reasons for leaving hibernation?
To prevent infections from the gut microbiome, to restore stored energy and to reproduce.
What are the 2 forms of defensive chemical production?
Synthesising toxins using metabolic processes or accumulating toxins from food.
Why are organisms struggling to adapt during the Anthropocene?
The level of environmental change is exceeding the capacity of developmental, genetic and demographic mechanisms that populations have evolved to deal with change.
Define over-exploitation in the context of extinction.
Harvesting species from the wild at rates faster than natural populations can recover.
Why are species moving away from the Equator? At what rate is this occurring?
Due to global warming making lower latitudes uninhabitable. Species are moving at a median rate of 16.9km per decade!
What are the current estimates for the number of species lost per year?
11,000-58,000 species.
What is the tragedy of the commons?
The depletion and ultimately the collapse of a common but limited resource when individuals act selfishly to maximize personal gains.
What is an island habitat, in a biological context?
A patch of suitable habitat surrounded by an unfavourable environment that limits the dispersal of individuals.
Why are islands important?
They make up 5% of land area but contain 30% of world’s biodiversity hotspots and 50% of marine tropical diversity.
Which animals are the first to colonise an island?
Those with good dispersal traits.
As the number of species on an island increases, what happens to the likelihood of other species arriving?
The likelihood decreases.
Define speciation.
An evolutionary process by which populations diverge to become distinct species.
Define adaptive radiation.
Organisms diversifying rapidly from an ancestral species into a multitude of new forms to exploit empty niches.
Define endemism.
The ecological state of a species being unique to a defined geographical location.
What triggers island gigantism?
The ecological release from large competitors and predators.
What triggers island dwarfism?
The ecological release from predators and resource limitation.
What are some morphological adaptations to parasitism?
Structures for host attachment and penetration.
Dorso-ventral flattening (to avoid grooming).
What are some physiological adaptations to parasitism?
Strong, impermeable cuticle (Nematodes).
Antienzyme production (Helminthes).
Reduction in sensory organs, nervous/digestive systems and locomotion apparatus.
High fecundity.
How do parasites avoid the host immune system?
Molecular mimicry - an “invisibility cloak”.
What are some parasitic behavioural adaptations?
Host finding behaviour.
Periodic behaviours - following a cyclic stimulus.
Host modifying behaviours.
What is the Allee Effect?
Warder Allee (1885 -1955) observed that under-crowding and NOT competition limited population growth for some species. Examples include passenger pigeons.
