BS218 - Chapters 15-16

adaptive radiation

an evolutionary expansion in which a group of organisms takes on new ecological roles and forms new species and higher taxonomic groups

allopatric speciation

the formation of new species from populations that are geographically isolated from one another

amphibian

a class of cold-blooded vertebrates made up of frogs, toads, salamanders, newts, and caecilians

analogous trait

of or referring to a characteristic shared by two groups of organisms because of convergent evolution, not common descent

behavioral isolation

when species are reproductively isolated from others due to differences in behavior

biological species concept

the idea that a species is defined as a group of populations that can interbreed but are reproductively isolated from other such groups

Cambrian explosion

a major increase in the diversity of life on Earth that occurred about 530 million years ago, during the Cambrian period; this lasted 5-10 million years, during which time large and complex forms of most living animal phyla appeared suddenly in the fossil record

clade

group of organisms that includes a single ancestor and all of its descendants

convergent evolution

evolutionary change that occurs when natural selection causes distantly related organisms to evolve similar structures in response to similar environmental challenges

evo-devo

evolutionary developmental biology

evolutionary tree

represents the evolutionary relationships among a set of organisms or groups of organisms, called taxa

family

in reference to biological classification systems, the level in the Linnaean hierarchy above genus and below order

genetic heritage

a particular set of genes and alleles that is typical of a species but different from that of all other species

genus (pl. genera)

in reference to biological classification systems, the level in the Linnaean hierarchy above species and below family

geographic isolation

the physical separation of populations from one another by a barrier such as a mountain chain or a river; these often cause the formation of new species, as when populations of a single species become physically separated from one another and then accumulate so many genetic differences that they become reproductively isolated from one another

homeotic trait

master regulator genes that direct the development of particular body segments or structures

kingdom

in reference to biological classification systems, the level in the Linnaean hierarchy above phylum and below domain; generally, there are six of these recognized: Bacteria, Archaea, Protista, Plantae, Fungi, and Animalia

lineage

a group of closely related individuals, species, genera, or the like, depicted as a branch on an evolutionary tree

Linnaean hierarchy

the classification scheme used by biologists to organize and name organisms; its eight levels - from the most inclusive to the least - are domain, kingdom, phylum, class, order, family, genus, and species

macroevolution

the rise and fall of major taxonomic groups due to evolutionary radiations that bring new groups to prominence and mass extinctions in which groups are lost; the history of large-scale evolutionary changes over time

mantle

the layer of Earth’s interior that sits just below the crust and extends to the core; it is composed of hot, semisolid rock

mass extinction

an event during which large numbers of species become extinct throughout most of Earth

morphological species concept

the idea that most species can be identified as a separate and distinct group of organisms by the unique set of morphological characteristics they possess

most recent common ancestor

the ancestral organism from which a group of descendants arose

node

the moment in evolution, depicted as a point on an evolutionary tree, at which one lineage splits, or diverges, into two separate lineages (such as Archaea and Eukarya)

order

in reference to biological classification systems, the level in the Linnaean hierarchy above family and below class

phylogenetics

the study of evolutionary relationships between organisms

phylum

in reference to biological classification systems, the level in the Linnaean hierarchy above class and below kingdom

plate tectonics

a theory suggesting that Earth’s crust is composed of several interlocking plates; several geologic factors can cause these plates to shift position over time, resulting in the movement of continents

prezygotic barrier

a barrier that prevents a male gamete (like a human sperm cell) and a female gamete (like a human egg cell) from fusing to form a zygote

postzygotic barrier

a barrier that prevents zygotes from developing into healthy offspring

polyploidy

of or referring to a cell or organism that has three or more complete sets of chromosomes (rather than the usual two complete sets). Populations of these individuals can rapidly form new species without geographic isolation

radioisotope

an unstable, radioactive form of an element that releases energy as it decays to more stable forms at a constant rate over time

reproductive isolation

a condition in which barriers to reproduction prevent or strongly limit two or more populations from reproducing with one another. Many different kinds of reproductive barriers can result in this, but it always has the same effect: no or few genes are exchanged between the reproductively isolated populations

scientific name

the unique two-part name given to each species that consists of, first, a Latin name designating that species; these are traditionally italicized

shared derived traits

an evolutionary novelty shared by an ancestor and its descendants but not seen in groups that are not direct descendants of that ancestor

speciation

the splitting of one species to form two or more species that are reproductively isolated from one another

species concept

members of populations that actually or potentially interbreed in nature, not according to similarity of appearance

sympatric speciation

the formation of new species from populations that are not geographically isolated from one another

taxonomy

the branch of biology that deals with the naming of organisms and with their classification in the Linnaean hierarchy

tetrapod

any terrestrial vertebrate that has four limbs; amphibians, birds, and mammals are examples

vertebrate

animals with a vertebral column and a cranium

vestigial organ

a structure or body part that served a purpose in an ancestral species but is currently of little or no use to the organism that has it