04 PPT NOTES Speciation_and_Phylogeny

Serotonin

A brain chemical that mediates behavior and is responsible for the transformation from solitary to gregarious behavior in desert locusts.

Pre-zygotic barriers

Factors that prevent mating or fertilization between different species, including temporal, behavioral, mechanical, and gametic isolation.

Post-zygotic barriers

Factors that occur after fertilization, preventing the hybrid zygote from developing into a viable/fertile adult. This includes issues such as hybrid inviability, hybrid sterility, and hybrid breakdown.

Phenotypic plasticity

The ability of an organism to change its phenotype in response to environmental conditions, seen in the transformation of desert locusts.

Gregarization

The behavioral transformation in locusts facilitating the switch from solitary to group living, mediated by serotonin.

DNA barcoding

A method used to identify cryptic species based on DNA sequence variation, revealing more species than previously recognized.

Common ancestry

The genetic relationship among species that having a recent shared ancestor leads to similarities in genetic makeup.

Adaptive radiation

The diversification of a group of organisms into forms filling different ecological niches, as seen in the evolution of vertebrates.

Monophyletic group (clade)

A group of organisms that includes a common ancestor and all its descendants. Ex: The clade archosauria

Paraphyletic group

A group including a common ancestor but not all of its descendants. Ex: “Reptiles” excludes birds even though birds descended from reptiles.

Polyphyletic group

A group of organisms that do not share a recent common ancestor, meaning that it includes multiple lineages that are not closely related. Ex: Bats and birds are grouped together based on flight, even though they do not share a common ancestor

Molecular clock

A technique that uses the mutation rates of biomolecules to deduce the time of divergence between species.

Phylogenetic tree

A diagram that represents the evolutionary relationships among various biological species based on similarities and differences in their physical or genetic characteristics.

Shared ancestral traits

Characteristics inherited from a common ancestor that are present in multiple descendants. Ex: Backbones

Shared derived traits

Traits that evolved and are unique to a particular clade, not found in the earlier common ancestor. Ex: Hair, Feathers

Shared derived traits

Which traits are phylogenic trees based on?

Reproductive isolation

The inability of species to breed successfully with related species, preventing gene flow and leading to speciation.

Gregarious phase

The phase of desert locusts where they form swarms and exhibit high levels of social interaction, influenced by environmental conditions.

Allopatric speciation

A form of speciation that occurs when populations are geographically isolated from one another, leading to the divergence of species.

Sympatric speciation

A form of speciation that occurs when populations diverge while living in the same geographic area, often due to behavioral differences, ecological niches, or reproductive isolation mechanisms.

Morphological species concept

A classification system that defines a species based on distinct morphological traits, including physical characteristics such as size, shape, and color.

Biological species concept

A classification system that defines a species as a group of organisms that can interbreed and produce fertile offspring, isolating them from other such groups.

Ecological species concept

A classification system that defines a species based on its ecological niche, focusing on the role and adaptations of organisms in their environment.

Phylogenetic species concept

A classification system that defines a species based on its evolutionary history and genetic relatedness, emphasizing the importance of shared ancestry and genetic differences in the identification of distinct species.

Primary hybrid zones

Regions where two species are drifting apart, speciation occurs with trace amounts of mixing.

Secondary hybrid zones

Regions where previously separated species come back into contact and interbreed after a period of geographic isolation, allowing for the mixing of distinct genetic backgrounds and potentially leading to the development of hybrid offspring.

Reinforcement hybrid zones

Regions where two species in secondary hybrid zones reinforce their reproductive isolation through natural selection, favoring traits that reduce hybridization and increase the success of purebred individuals.

Fusion hybrid zones

Regions where previously diverged species come back into contact and begin to interbreed, ultimately leading to a merging of the two gene pools.

Stability hybrid zones

Regions where two species maintain distinct identities while hybridization occurs; hybrids may be fit in certain environments but do not replace the parental species.

Gradualism

A model of evolution in which gradual change occurs over long periods, leading to the development of new species through a slow and steady accumulation of small genetic changes.

Punctuated equilibrium

A model of evolutionary change characterized by long periods of stability in species interspersed with short bursts of significant evolutionary change, often associated with rapid speciation events.

Opportunity and Innovation

What determines rate of speciation?

Adaptive radiation

The diversification of a group of organisms into forms that fill different ecological niches, often occurring rapidly when new environments are colonized, allowing species to exploit various resources.

Rule of Maximum Parsimony

A principle in phylogenetics that suggests the simplest explanation, or the one that requires the least number of evolutionary changes, is preferred when constructing a phylogenetic tree.

Rule of Maximum Likelihood

A statistical method used in phylogenetics to estimate the parameters of a model that makes the observed data most probable, often used to infer evolutionary relationships.

Cladistics

A method of classification based on the construction of phylogenetic trees that represents the evolutionary relationships among species, emphasizing shared derived traits and common ancestry.

Vertebral column, jaws, lungs, 4 limbs, amniotic egg

What are the shared ancestral traits of mammals?

Hair/Fur, Mammary glands, 3 middle ear bones

What are the shared derived traits of mammals?

Parsimony

The principle that the simplest explanation, or the one that requires the least number of evolutionary changes, is preferred when organizing organisms into a phylogenetic tree.

Maximum Likelihood, Maximum Parsimony

What are the two principles used when building phylogenetic trees using molecular systematics?

Sequences not under selection evolve at a constant rate over time.

In phylogeny, why is it crucial to compare genetic sequences not under selection?

Mitochondrial DNA

What part of the genome is checked in determining evolutionary relationships?

Intrasexual selection

A type of natural selection where individuals within the same sex compete for mates, often leading to the development of traits that enhance competitive ability, such as larger size or aggressive behavior.

Intersexual selection

A type of natural selection where individuals of one sex choose mates between the other sex based on certain traits, leading to the evolution of characteristics that enhance attractiveness, such as elaborate plumage in birds.