Coevolution and Speciation Processes

Species Interactions and Coevolution

• Adaptations in one species can drive adaptations in another, creating a feedback loop.
• This reciprocal evolutionary change is called coevolution.

Evolutionary Effects of Development Genes

• Developmental genes control the rate, timing, and pattern of organismal development.
• Changes in these genes can lead to significant changes in body form.

Changes in Rate and Timing

• Heterochrony is an evolutionary change in the rate or timing of developmental events.
• Differences in the relative growth rates of parts of the body, lead to the contrasting shapes of human and chimpanzee skulls.

Speciation Rates- Punctuated Equilibrium vs. Gradualism

• Punctuated equilibrium: Long periods of little change punctuated by short bursts of rapid evolutionary change.
• Gradualism: Gradual, steady change over long periods.
• These are two contrasting models for how speciation occurs.

Speciation Processes and Rates

• Punctuated equilibrium:
  • Sexually reproducing populations experience long periods of little change.
  • Rapid bursts of branching speciation (cladogenesis) are localized and rare events.
  • Phyletic gradualism:
    • Evolution occurs steadily along a lineage (anagenesis).

Parapatric Speciation

• Part of a population enters a new habitat bordering the range of the parent species.
• The border group develops unique traits.
• Hybrids form between the populations
• A common example is the Little greenbul of Cameroon (different populations developing traits in different environments).

Sympatric Speciation

• Populations diverge genetically within the same geographic area.
• Cichlids of Cameroon and Lake Ejagham are an example.
• Populations adapt differently to varying microenvironments.
• Example is that of cichlids in different environments of Cameroon populations and Lake Ejagham.
• A change in ecological strategy can result in speciation.

Allopatric Speciation

• Geographic isolation creates separate populations that diverge genetically over time.
  • Dispersal, and vicariance are the two main ways populations can be isolated geographically.
• Over time, separate populations evolve significant differences and can no longer interbreed.

Biological Species Concept

• A group of populations whose members can interbreed to produce fertile offspring.
• Members of the same species can interbreed, or have the potential to interbreed.
• Speciation occurs when breeding becomes impossible.

Macroevolution and Microevolution

• Microevolution is the change in allele frequencies within a population.
• Microevolution has a key role in macroevolution , driving the evolution of new species.

Evidence of Biological Evolution and Natural Selection

• Anatomical Record:
  • Homologous structures are similar in structure, share evolutionary origin, but not necessarily in function (e.g., forelimbs of mammals).
  • Analogous structures have similar functions,but do not share evolutionary origins (e.g., wings of birds and insects).
  • Vestigial structures are reduced or diminished structures that had important functions in an ancestor.

Convergent Evolution

• Organisms that are not closely related develop similar characteristics due to similar environmental pressures.

Artificial Selection in Plants

• Humans have selected for desirable traits in plants such as broccoli, cabbage, kale and Brussels sprouts.

Coyotes, Wolves, and Dogs

• New DNA research indicates that eastern coyotes are a mixture of coyote, wolf, and dog genes, not a distinct species.
• Genetic variation exists in coyote populations.

Bush Dog

• The bush dog is a canine found in Central and South America.
• It's evolutionarily closer related to the maned wolf, than the African wild dog or other related species.
• The bush dog evolved partially-webbed toes, to facilitate aquatic foraging.

Dog Domestication

• Findings indicate the origin of a small dog type before domestication emerged from a wolf populations, and not as a result of human-selected preferences for small breeds.
• Genetic mutations influencing body size are evident in early wolf ancestors.

The Organization of Life

• The Linnaean taxonomy (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species) groups organisms by shared characteristics and evolutionary relationships.
• A paleontological species uses morphology to define species instead of interbreeding criteria.

This quiz explores the intricate dynamics of species interactions, coevolution, and the effects of developmental genes on evolution. It also covers the contrasting models of speciation, including punctuated equilibrium and gradualism. Test your knowledge on how these concepts shape the evolutionary timeline of organisms.