Patterns of Evolution
Notes on Patterns of Evolution
Notes on Patterns of Evolution
Divergent Evolution
Divergent Evolution
- Species with a common ancestor evolve into separate species as they adapt to a range of different habitats that have become available. Often as a result of changes in abiotic conditions such as changes in salinity, geography etc...When multiple species evolve this is known as Adaptive Radiation
Convergent Evolution
Convergent Evolution
- when species from different ancestral backgrounds living in the same environment come to look similar
- shark(fish); penguin (bird); dolphin(mammal); ithyosaurus(reptile)
Four different classes of organism which have all evolved to live in the sea. Analogous structures have evolved to suit the environment.
Four different classes of organism which have all evolved to live in the sea. Analogous structures have evolved to suit the environment.
Parallel Evolution
Parallel Evolution
- Development of species from a common ancestor along similar evolutionary paths due to natural selective pressures acting on each species in a similar way. Often involves evolution of geographically separated groups in such a way that they show morphological resemblances.
Otter
Otter
Mammal evolved to occupy an aquatic niche
Platypus
Platypus
Marsupial evolved to adapt to a similar aquatic habitat and share similar features
Convergent and Divergent Evolution
Convergent and Divergent Evolution
Brief comparison of these two different patterns of evolution
Co-Evolution
Co-Evolution
- the process of reciprocal evolutionary change that occurs between pairs of species or among groups of species as they interact with one another. The activity of each species that participates in the interaction applies selection pressure on the others.
The Monarch caterpillar and Milkweed are an example of co-evolution
Co-evolution of the Hawk moth and Madagascar Star Orchid
Co-evolution of the Hawk moth and Madagascar Star Orchid
http://faculty.washington.edu/jrw/110/darorch.htm
Rates of Evolution
Rates of Evolution
- Punctuated Equilibrium - evolution consisting of long periods of stability followed by periods of rapid change due to one or a few huge changes occur ( maybe environmental or through mutation)
- Gradualism(Sequential Evolution)- change is slow and consistent were small variations that fit an organism better to its environment are selected for.
Homologous Structures and Analogous Structures
Homologous Structures and Analogous Structures
Identifying between homologous and analogous structures can help identify evolutionary processes followed in the evolution species - divergent or convergent evolution.
Identifying between homologous and analogous structures can help identify evolutionary processes followed in the evolution species - divergent or convergent evolution.
Homologous Structure
Homologous Structure
Structures which have a similar evolutionary origin, and therefore a similarity in the basic anatomical structure, but have adapted to suit different functions as a result of evolving to inhabit different habitats
Analagous Structures
Analagous Structures
Structures which have a similar purpose but often very different internal organisation (anatomy - either in plants or animals) due to their different evolutionary origins.
