Lecture 17 and 18 - Macroevolution Flashcards
Adaptation
A characteristic that enhances the survival or reproduction of the organism that bears it (relative to the ancestral state)
Snake Jaw kinesis
Adaptation in snakes where they can dislocate their jaw to eat bigger things
Post copulatory cannibalism in widow spiders
adaptation that after mating male spiders will lauch themselves into the jaws of the female that eats him
A male who offers himself the fertilised eggs more likely to be used
Adapted for competition with other males
Coadaptation
Complex characters undergoing mutually inter-dependent adjustments in response to the same natural selection pressures
Examples of coadaptation
Mimicry in butterflies adapts across species
Correlated progression of complex features in territorialisation
Exaptation
Feature that has been co-opted to serve a new function
Examples of Exaptation
Penguin wings formerly used for flying, co-opted to underwater swimming
Bird feathers may have initially evolved for insulation and thermoregulation
What are ways in which you can test weather a character is an adaptation?
Experimentally investigating through manipulation
Comparative method: comparing independent evolution of the same feature in related groups
Example of recognizing adaptations through experimentally investigating through manipulation?
Male barn swallows
Cutting/extending their tails to observing the number of offspring
Found out tail size does have a correlation with offspring and therefore adaptation
Spandrals of San marco
Theory that just because something has a function may not mean that it is an adaptation, it may just be a byproduct of something else.
Why do adaptations have limits
There is a limit to an organisms available resources investment in different strategies can lead to evolutionary trade-off
For example, cheetahs cannot get any faster as any other changes that would make them faster would decrease the fitness of another trait
Morphodynamics
Interaction between environment, functional morphology, developmental constraints, historic constraints (phylogeny), and time
Phylogenetic constraints
Limits of what characters can develop due to going down a particular evolutionary pathway
Example of phylogenetic constraints
Larynheal nerve
Travels further distance than it needs to up the neck of animals with large necks
What are the 3 types of constraints in morphodynamics?
Functional constraints
Phylogenetic constraints
Fabricational constraints
Functional constraint
Limitation on the variation expressed in a phenotype in a phenotype because many variants have impaired function and reduce fitness
Fabricational constraint
A restriction that prevents a lineage from evolving a trait due to the properties of biological materials
Example of functional constraint
Insects have tubes in their body for oxygen to diffuse around their body
This puts a limitation on insect body size
Example of a fabricational constraint
Cannot construct diamond teeth
Microevolution
Changes in a population i.e. mutation, migration, genetic drift, natural selection
Macroevolution
Change above species level i.e. adaptive radiation, rates of diversification and change, mass extinction, etc.
What processes affect microevolution and macroevolution?
The process involved in the two are identical, but they occur in a different scale and over longer periods of time
Evolutionary trend
Any sustained tendency for evolutionary change in a particular direction (from generations to millions of years)
Passive trend
A trend goes in no particular direction
