Issues in Bio: Chapter 16 "Speciation and Macroevolution."

Macroevolution

larger-scale changes in a population that occur over a relatively long periods of time.

What is speciation due to?

changes in the gene pool and the divergence of two populations genetically.

Biological Species Concept

the members of a species interbreed and have a shared gene pool, and each species is reproductively isolated from the other.

According to the biological species concept how does gene flow occur?

it occurs between the same species.

Common Ancestor

a single ancestor for two or more different groups. species in the same genus.

Prezygotic isolating mechanisms

-operate before fertilization of a zygote occurs.

-they prevent reproductive attempts, and make it unlikely that fertilization will be successful if mating is attempted.

What are different Prezygotic barriers?

1.) habitat isolation,

2.) temporal isolation,

3.) behavioral isolation,

4.) mechanical isolation,

5.) gametic isolation

Habitat Isolation

two species occupy different habitats and thus encounter each other rarely, or not at all

Temporal isolation

two or more species reproduce in the same habitat, but at different times.

Behaviorial isolation

many animal species have courtship that allow males and females to recognize another.

Mechanical Isolation

when animal genitalia or plant floral structures are incompatible, reproduction cannot occur

Gamete Isolation

sperm cannot reach or fertilize egg

4 Postzygotic Barriers

1.) zygote morality

2.)Hybrid sterility

3.) F2 Fitness

Zygote Mortality

fertilization occurs, but zygote does not survive (miscarriage)

Hybrid Sterility

hybrid offspring mature but are sterile as adults

F2 fitness

Hybrid is fertile, but offspring of hybrid (F2) has lower fitness and is sterile

Two Models of Speciation

allopatric and sympatric speciation

Allopatic speciation

formation of new species due to geographic isolation

Sympatric speciation

The formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population. No geographic barrier is present. (live in the same location)

Polyploidy is an example of...

Sympatric. condition in which an organism has extra sets of chromosomes...

Adaptative Radiation

many similar but distinct species evolve from one ancestor in a short period of time

finches or lemurs

Fossils

traces of organisms that existed in the past

Paleontology

the science dedicated to discovering and studying the fossil record and from that, making decisions about the history of species.

Geological Time Scale (GTS) -SEE TABLE 16.1-

divides the history of life on earth into Eras, then periods, and then Epochs.

How many periods does the Era Cenozoic have, and What are they? Is this the only era that divides it's periods into Epochs?

2; Quaternary and Tertiary; Yes, to signify the humans.

Gradualistic model

Darwin thought evolutionary changes occurred gradually

Often shows evolutionary history as an evolutionary tree

Difficult to indicate when speciation has occurred because of transitional links

Punctuated Equilibrium

-paleontologists prefer this model.

-A period of equilibrium is interrupted by speciation.

-suggests transitional links are less likely to become fossils, and less likely to be found.

Mass Extinctions

The disappearance of a large number of species in a relatively short period of geological time.

At the ends of which 4 periods were mass extinctions? There is an epoch too, which one is this?

Ordovician, Devonian, Permian, Triassic, and Cretacious. THE PLEISTOCENE EPOCH was the mass extinction of mammals.

Continental drift

-contributor to several mass extinctions.

-Movement of Continents

Why do the continents drift?

explained by plate tectonics. the earth's crust is positioned on slabbed plates that float on a hot mantle layer.

When was Pangea formed?

Paleozoic Era. (250 million years ago) During the permian mass extinction.

When did the meteor impact cause a mass extinction?

during the Cretaceous period.

What are the three causes of mass extinctions?

Continental drifts, Meteor Impacts, and Climate Change.

Systematics

study of the diversity of life and the evolutionary relationships between organisms

Phylogeny

Evolutionary history of a species; determined by a combination of data from the fossil record; comparative anatomy and development, and emphasis on molecular data.

Taxonomy

branch of biology that identifies, names, and classifies species based on their natural relationships

Taxon

a group of organisms at a particular level in a classification system

In Domain Eukarya, what is the order of the species "Homo Sapiens"?

Primates.

SGFOCPKD

species, genus, family, order, class, phylum, kingdom, domain (supergroups)

Supergroup

A new taxonomic group that is being developed to explain evolutionary relationships between eukaryotic organisms based on DNA analysis.

Phylogenic Trees

diagram that indicates common ancestors and lines of descent.

At what part of the phylogenic tree does ancestor have traits that are shared by the rest of the tree?

the base.

How is the Phylogenic Tree organized from the base up?

Order, Family, Genus, Species.

Homologous structures

Structures in different species that are similar because of common ancestry.

Why is deciphering homology difficult?

because of convergent evolution

Convergent evolution

the acquisition of the same biological trait in unrelated lineages

Analogus structures

have the same function, but different groups.

How do analogous traits arise?

adaptations to the same type of environment.

Cladistics

A phylogenetic classification system that uses shared derived characters and ancestry as the sole criterion for grouping taxa.

Cladogram

Diagram that shows the evolutionary relationships among a group of organisms

Clade

A group of species that includes an ancestral species and all its descendants.

Two major differences between Linnaean and Cladistic classification.

1) Clades are hierarchal, just like Linnaean. But, there may be more clades than Linnaean categories.

2) Taxons are not necessarily equivalent in the Linnaean system.

Five-kindom system

plantae, animalia, fungi, protists, and monera (bacteria)

Which two domains are the prokaryotes organized in?

Bacteria and Archaea

Domain Eukarya

Domain of all organisms whose cells have nuclei, including protists, plants, fungi, and animals

Domain Bacteria

One of the three domains of life; contains prokaryotic cells that differ from archaea because they have their own unique genetic, biochemical, and physiological characteristics.

Domain Archaea

Any of various single-celled prokaryotes genetically distinct from bacteria, often thriving in extreme environmental conditions