Lecture 8 Flashcards
What does fitness refer to?
Ability to pass genes to offspring
What does fitness reflect?
How well adapted the individual is to the conditions it faces
Species lifespan of mammals
1-2 million years
Species lifespan of marine invertebrates
5-10 million years
Species lifespan of diatoms
8 million years
How do closely related species that are generally placed in the same genus become separated?
Through speciation events
Sympatric speciation
When can it happen?
Speciation within a single region
If there is a very strong preference of “like for like” within the population or if populations become separated by non-geographic barriers
Allopatric speciation
Have to be physically separated
Heterochronic evolution
Any evolution related to changes in rate of development of the organism
Pedomorphosis
Sexual maturity in a juvenile body; adults are more like ancestral juveniles
Peramorphosis
Adult development is beyond that in the ancestor
Phylogeny
Reconstruction of the evolutionary history of a group/groups of organisms, and their relationships
Phyletic gradualism
Gradual changes in lineages, with change through time within a species
Punctuated equilibrium
Features of a species are relatively static, and most evolution happens at speciation events
Homologous structures
Shared inherited structures
What can molecular divergence do?
Produce a phylogeny based on e.g., mitochondrial DNA and plot it against the geological time scale
Convergent evolution
Organisms that are not closely related have independently evolved similar features, or features that serve the same purpose
Divergence
Characters evolved independently to become less similar
Evolutionary radiation
Rapid increase in the diversity of a group over a relatively short time period
What is evolutionary radiation often due to? Give examples.
Often due to opportunity, such as extinction of competitor group, occupation of a new territory, or evolution of a novel adaptation
Living fossils
Idea that an extant organism is “the same” as a related species only known from the fossil record
Problem with concept of living fossils
They are never actually the same species, even if related (nothing is ever static)
Can be problematic because it is often used because something “looks prehistoric”
When can the concept of living fossils be useful?
If it allows us to recognize groups that have been successful with same basic plan over long time periods
