Biogeography Exam 3 comp.

Cosmopolitan species

Species with very broad geographic distributions across multiple regions or continents, often generalists with wide environmental tolerance and high dispersal ability

Endemic species

Species restricted to a specific geographic area, often associated with isolation and specialized ecological requirements

Autoendemic

A species that evolved within the area where it is currently found and has a restricted distribution

Alloendemic

A species that originated elsewhere but now has a restricted range due to contraction or isolation

Autochthonous species

Species that originated and evolved in the region where they are currently found

Allochthonous species

Species that originated outside their current region and arrived through dispersal or migration

Taxonomic relict

A species that is the last surviving member of a once diverse lineage with few or no close relatives

Biogeographic relict

A species that was once widespread but is now restricted to a small portion of its former range

Neoendemic

A recently evolved species with a restricted geographic range, often associated with recent speciation events

Paleoendemic

An ancient species with a formerly broad distribution that is now restricted due to range contraction

Provincialism

The occurrence of distinct biotas in different geographic regions due to isolation and evolutionary divergence

Patterns of provincialism

Stronger in regions separated by major barriers such as oceans or mountains and in areas with long periods of isolation

Biogeographic regions

Large areas defined by distinct assemblages of species and evolutionary histories shaped by isolation and environmental factors

How biogeographic regions are defined

Based on species composition, levels of endemism, phylogenetic relationships, and historical isolation

Evidence for biogeographic regions

Includes taxonomic similarity, phylogenetic data, fossil records, geographic barriers, and plate tectonic history

Disjunction

A pattern where closely related species or populations are separated by large geographic distances

Vicariance

A process where a population is split by the formation of a barrier leading to divergence

Dispersal

Long distance movement of organisms across barriers resulting in disjunct distributions

Extinction driven disjunction

A pattern where intermediate populations go extinct leaving isolated populations

Biotic interchange

The exchange of species between previously isolated regions due to the removal of barriers

Great American Biotic Interchange (GABI)

A major exchange of species between North and South America after the formation of the Isthmus of Panama about 3 million years ago

Isthmus of Panama

Land bridge that connected North and South America enabling GABI and altering ocean circulation

Differential success in GABI

North American species were generally more successful invaders in South America than vice versa

Reasons for North American success

Included greater competition, more advanced predators, and adaptation to variable climates

South American fauna limitations

More specialized and less competitive due to long isolation and fewer predators

Convergent evolution

Independent evolution of similar traits in unrelated lineages due to similar environmental pressures

Importance of convergence in biogeography

Demonstrates how similar environments shape similar adaptations despite different evolutionary histories

Systematics

The scientific study of evolutionary relationships and classification of organisms

Importance of phylogeny

Allows reconstruction of evolutionary history, identification of relationships, and understanding of biogeographic patterns

Lamarckism

Early evolutionary theory proposing inheritance of acquired characteristics

Darwinism

Theory of evolution by natural selection and common descent explaining adaptation and diversification

Evolutionary taxonomy

A classification approach that considers both evolutionary relationships and degree of difference

Data used in phylogenies

Morphological traits, molecular data such as DNA sequences, behavioral traits, and fossil evidence

Clade

A group consisting of an ancestor and all of its descendants

Terminal taxon

A species or group located at the tip of a phylogenetic tree

Root

The base of a phylogenetic tree representing the common ancestor of all taxa in the tree

Node

A branching point representing a divergence event from a common ancestor

Branch

A line representing an evolutionary lineage

Most recent common ancestor

The most recent individual from which two or more taxa are descended

Sister group

Two lineages that share an immediate common ancestor and are each other's closest relatives

Ingroup

The main group of organisms being studied in a phylogenetic analysis

Outgroup

A taxon used as a reference point to root a phylogenetic tree and determine ancestral traits

Cladogram

A phylogenetic tree that shows relationships among taxa without indicating time or amount of change

Phylogram

A tree where branch lengths represent the amount of evolutionary change

Chronogram

A tree where branch lengths represent time since divergence

Rooting a tree

The process of determining the direction of evolution by identifying the common ancestor using an outgroup

Hard polytomy

A node with more than two descendant lineages representing a true simultaneous divergence

Soft polytomy

A node with multiple branches due to uncertainty or insufficient data

Phenetics

A method that groups organisms based on overall similarity without considering evolutionary relationships

Cladistics

A method that classifies organisms based on shared derived characteristics and common ancestry

Statistical phylogenetics

Methods that use mathematical models to estimate phylogenies such as maximum likelihood and Bayesian inference

Synapomorphy

A shared derived trait that defines a clade and indicates common ancestry

Apomorphy

A derived trait that differs from the ancestral condition

Plesiomorphy

An ancestral trait shared by multiple taxa

Autapomorphy

A derived trait unique to a single taxon

Symplesiomorphy

A shared ancestral trait that is not useful for defining clades

Monophyletic group

A group that includes an ancestor and all of its descendants

Paraphyletic group

A group that includes an ancestor but not all of its descendants

Polyphyletic group

A group composed of unrelated organisms that do not share a recent common ancestor

Homoplasy

A similarity in traits not due to shared ancestry

Causes of homoplasy

Include convergent evolution, parallel evolution, and evolutionary reversals

Example of homoplasy

Wings in bats and birds evolved independently but serve similar functions

Molecular clock

A method that uses mutation rates to estimate the timing of evolutionary divergence

Molecular dating using fossils

Uses fossil evidence to calibrate molecular clocks and assign absolute ages to divergence events

Primary islands

Islands that have never been connected to continents and typically originate from volcanic activity

Continental islands

Islands that were once connected to continents and became isolated due to rising sea levels or tectonic activity

Other island types

Include coral atolls, barrier islands, and land bridge islands formed during periods of low sea level

Island syndrome

A set of predictable evolutionary changes on islands including body size shifts, reduced dispersal, and loss of defenses

Ecological release

Expansion of a species niche due to reduced competition or predation

Demographic release

Increase in population size due to reduced mortality or competition

Species area relationship

A pattern where larger islands support more species due to greater habitat diversity and lower extinction rates

Species isolation relationship

A pattern where more isolated islands have fewer species due to reduced immigration rates

Species turnover

The continual replacement of species on an island through immigration and extinction

Equilibrium theory of island biogeography

A model proposing that species richness is determined by a balance between immigration and extinction rates

General model of ETIB

Immigration rates decline as species accumulate while extinction rates increase leading to an equilibrium number of species

Assumptions of ETIB

Species are ecologically equivalent and immigration and extinction rates depend on island size and distance

Dynamic nature of ETIB

Species composition changes over time even if total species number remains constant

Strengths of ETIB

Simple and predictive framework for understanding island biodiversity patterns

Weaknesses of ETIB

Does not account for speciation, species differences, or complex ecological interactions

Immigration rate

The rate at which new species arrive on an island, higher for closer islands

Extinction rate

The rate at which species are lost, higher on smaller islands

Rescue effect

Immigration reduces extinction by replenishing declining populations

Target area effect

Larger islands receive more immigrants because they present a bigger target for dispersing organisms

Small island effect

On very small islands species richness may not increase with area due to extreme limitations

Conservation biogeography

The application of biogeographic principles to conserve biodiversity and manage ecosystems

Geographic patterns of extinction

Extinctions are highest on islands and in regions heavily impacted by humans

Taxonomic patterns of extinction

Vertebrates and large bodied species are disproportionately affected

Island extinctions

Common due to small populations, limited ranges, lack of predator defenses, and human impacts

Linnean shortfall

Lack of knowledge about the total number of species on Earth

Wallacean shortfall

Lack of knowledge about species geographic distributions

Prestonian shortfall

Lack of knowledge about species abundances and population sizes

Darwinian shortfall

Lack of knowledge about evolutionary relationships among species

Habitat loss and fragmentation

Destruction and division of habitats leading to reduced population sizes and isolation

Invasive species

Non native species that outcompete, prey on, or introduce diseases to native species

Pollution

Introduction of harmful substances into ecosystems that negatively affect organisms and habitats

Exploitation

Overharvesting of species for food, trade, or other uses leading to population decline

Climate change

Long term changes in climate that alter habitats, shift ranges, and increase extinction risk

Geographic range collapse

The contraction of a species range prior to extinction

Demographic hypothesis of range collapse

Population declines occur uniformly across the range

Contagion hypothesis of range collapse

Extinction spreads spatially from one area to another