Ornithology Chapters 2- ?

Terms and other important info from the textbook.

Classification

in an evolutionary context, the process by which scientists name organisms and assign them into larger groups based on their evolutionary relatedness

Phylogeny (Phylogenetic Tree)

a diagram that depicts the evolutionary relationships connecting a set of organisms

Species

basic unit of biological classification for birds. Criteria usually groups based on very similar traits, history of recent shared ancestors, and the continued ability to fully interbreed.

Subspecies

a distinct population or group of populations within a more widespread species that is distinguishable from other subspecies on the basis of one or more diagnostic traits

Monophyletic group

any group of organisms that include the most recent common ancestor of that group and all its past and present descendants

Clade

any group of organisms that includes the most recent common ancestor of that group and all of its past and present descendants

Binomial Name

naming system in biology in which each species is assigned a unique name of the species (Genus, species)

Lumping

informal term for changes in classification that involve merging into one species two or more taxa that were preciously each considered to be a separate species

Splitting

informal term for changes in classification that involve separating into different species populations that were previously considered to be part of a single species

Speciation

the evolutionary process by which one ancestor lineage splits into two or more descendant species

Population

in ornithology, a group of interbreeding birds of the same species that live in the same place at the same time

Species Concept

set of criteria systematists use when deciding whether two populations are the same species or different species

Biological Species Concept

a classic species concept that places greatest emphasis on whether or not members of two populations retain the ability to interbreed

Phylogenetic Species Concept

a species concept that focuses on the history of a related set of organisms, in which a species is usually defined as the smallest group descended from a common ancestor that share a distinguishable feature that separates them from other groups

Allopatric

populations that occur in separate regions with no geographic overlap

Branches

lines on a phylogeny that trace the pathway of evolutionary lineages through time

Nodes

the points on a phylogeny where branches separate, usually representing points where an ancestral lineage splits into two or more descendant lineages

Sister Taxa

two groups (sometimes more) that are each other’s closest evolutionary relatives

Character

in avian systematics, any heritable trait that can be compared among different groups of birds

Range Disjunction

a pattern of geographic distributions in which two or more occupied areas are separated by substantial intervening areas where the species is not found

Phylogeography

the scientific study of the evolutionary relationships of populations and species across space, usually as inferred from genetic information

Latitudinal Diversity Gradient

the general rule that in most groups of organisms, species diversity is greatest in the tropics and steadily decreases towards the earth’s polar regions

8 Biogeographic Realms

1. Nearctic

2. Neotropical

3. Afrotropical

4. Palaearctic

5. Indomalayan

6. Oceanian

7. Australasian

8. Antarctic

Biogeographic Realms (definition)

a traditional classification of the earth’s terrestrial regions that groups them by their broadly similar faunas, floras, and evolutionary histories

Great American Interchange

the exchange of animals that commenced about 3 million years ago when a land bridge first connected the previously isolated continents of North and South America

Key Inoovation

a newly evolved trait that allows a lineage to take advantage of new ecological opportunities, and which results over time in that lineage diversifying into multiple species that are specialized for those new ecological niches

Sympatry

refers to organisms or groups of organisms that occur in the same place

Density-dependent diversification

the somewhat controversial concept of a feedback loop in which speciation within a group slows down over time as the number of species increases, since the presence of existing species blocks opportunities for new species to arise

Archosaurs

a large group of reptiles that includes the non-avian dinosaurs, pterosaurs, crocodiles, and birds

Maniraptora

a group that includes birds and their closest relatives within theropod dinosaurs

Pneumatized

filled with small air cells

Genome

a complete set of genetic material—DNA—within an individual bird

Molecular Clock

the idea that DNA changes accumulate at a relatively steady rate, and that the genetic differences among organisms can therefore be used to estimate the time in the past when they started to diverge from one another

Ghost Lineage

an evolutionary lineage that is inferred from a phylogeny, but for which no fossil evidence has been found

Crown Group

a special type of monophyletic group (clade) that includes all organisms descended from the last common ancestor of all living members of a larger clade

Ratite

a group of flightless birds defined by their absence of a keelbone (or carina), including the ostriches, kiwis, rheas, cassowaries, emus, and recently extinct moas and elephantbirds

Paleognaths

one of the two groups of living birds, containing all rattites as well as the extinct elephantbirds and moas

Neognaths

one of the two groups of living birds, containing all living birds expect the ratites

Gondwana

the name of the ancient southern super-continentof 180-600 million years ago that included most of present-day Africa, Antarctica, Australia, India, Madagascar, New Zealand, and South America