Biogeography

Dispersal

Movement of individuals from either a birth site to breeding site, breeding site to another, or movement with the potential to lead to gene flow. In biogeography, it’s only relevant if it results in immigration, expanding species distribution towards its fundamental geographic range

Requirements of Dispersal

Travel to a new area (departure cost/benefit),withstand unfavorable conditions during passage (transfer cost/benefit, can an animal withstand passing through an extreme climate?),establish a viable population upon arrival(establishment or settlement cost/benefit)

Type of Dispersal

1. Self powered (active) = purposeful behavior like flying

2. With the help of abiotic factors - non directional (passive) = the organism is carried by something else

3. With the help of other organisms - vectored (passive) = one organism is transported by another

Grinnellian Niche

soaciallt explicit, focus on non-interactive requirements for populations to thrive, measurable from distribution

Eltonian Niche

Focuses on community impacts, biotic interactions (like species functional roles)

Hutchinsonian Niche

Focus on non-interactive requirements, focuses on two types, funadamental (total range where a species CAN survive) and realized (actual range where species survives)

Limits to geographic range

Physical factors (temp, water,soil)- disturbance, dispersal, and time

Interactions with other organisms - competition, predation and parasitism, mutualism, multiple interactions

Law of the minimum

Idea that biological processes are limited by a single factor. Not we know that is too simple an idea because an organism can withstand low temps but not prolonged freezing, there’s no clear def of cold.

Metapopulations

Groups of populations of same species, connected by pockets of habitats

Environmental envelope

When data is extrapolated where things are located to a fixed range

Outline, dot, and contour maps

Outline - depicts range within boundary that depends on extent of knowledge

Dot - plot points where an organism has been recorded, verified by museum collections

Contour - show where similar levels of a variable are to show variation across a species range

Georeference

A numerical description in a coordinate system of place

What is biogeography?

The study of species distributions and characteristics and differences in functional attributes of species across their ranges

Advances in biogeography driven by…

1. Finding connections between divergent disciplines

2. Merging ecological knowledge from distinct local populations to discover emergent global patterns

The founding of biogeography is attributed to the age of exploration (18th and 19th century) and discovery of regionally distinct biotas

Types of Dispersal Routes

Corridors - route to allow of the movement of species by providing an environment similar to the 2 areas

Filters - more restrictive than corridors, it blocks passage of certain forms while allowing others to migrate freely (water around islands, less reptiles going east of islands for ex)

Sweepstakes routes - Barriers that must be passed by rare chance interchanges (long distance jump dispersals”

Type of range-expanding dispersal

Diffusion - slow range expansion usually due to generational mini movements of spreading beyond previous range

Secular migration - expansion occurring after many generations, providing more opportunity for evolutionary change

Jump dispersal - long distance dispersal from movement of individuals within a short period

Diffusion stages

Invasion and range expansion may be very slow, usually needing an invasion to the ecosystem and repeated dispersal events

Once established, its geographic range often expands at exponential rate

Eventually range expansion slows

Vicariance

Separation of a groups of organisms by a geographic barrier

Species def

An irreducible group whose members are descended from a common ancestor who all posses a combination of certain traits and can interbreed

Mutation

Ultimate source of variation : formation on new alleles

Types of mutation - deletion, insertion, inversion, substitution

Substitution : substitute one nucleotide

Deletion,insertion, inversion

Gene flow and Hybridization

Movement of alleles within or between populations because of dispersal or offspring, often slowing genetic divergence and natural selection. The organisms grow more alike and can possibly fuse as they grow more similar with more gene flow and hybridization

Genetic drift

A random change in the frequency of an allele, driven by founder effects which contributes to speciation (it can go up or down. It’s independent of natural selection)

natural and sexual selection

Species with traits that don’t support it to survive in an environment are killed so one trait becomes popular through this natural form of selection

Adaptive Radiation

The evolution of ecological diversity within a rapidly multiplying lineage, driven by natural selection made from mass extinctions, invasions, or development of key innovation(wings in birds)

Non-adaptive radiation

Creation of new species with very little ecological differentiation

Endemism

The occurrence of taxa with native distributions limited to a specific geographic location.

This area may be widespread even if locally rare or extremely tiny. It’s scalable

Provincialism

Geographic overlap of endemism across multiple taxa

Disjunction

Two or more related taxa or populations occurring in geographically separate areas

How can a species be endemic to a location?

1. They originated there and never dispersed

2. Their entire range has shifted after originating

3. Now they can only survive in a smaller part of their previous range

Autochtonous ce Allochthonous endemics

Auto - evolved in an area within their current distribution ( never moved despite passing of time)

Allo - originated somewhere else, dispersed to current locality

Neowndics vs paleoendemics

Neo - often recently originated taza that’s autochthonous

Paleo - taca that’s gone extinct elsewhere, often known as relics

Types of relicts

Taxonomic - remnants of a before, very diverse taxon

Biogeographic relicts - taxa that at one time had much wider distributions

Wallace’s Line

Line that Wallace believed was a boundary between provinces. For one taxon at a time, their boundaries overlapped with geologic or climate barriers

Biotic interchange

Land bridges always served more as a filter rather than as a corridor

migration is often unbalanced, with one side moving further into the other’s area than vice versa

Creation of Panama Canal connect the Atlantic and Pacific Ocean, creating a path for mixing of past isolated taxa

Common classification for evolution systematics

Phylogenetic systematics or cladisitcs. Uses one or more derived characters and focuses on lineages and common ancestry, not including overall similarity. Numerical phenetics (subtype) uses algorithms to determine overall similarity but tends to group taca wrong because of convergency characters and different rates of evolution between taxa

Paraphyletic vs Polyphyletic

Group that has common ancestor but not all descendants

Vs

Groups derived from one or more common ancestor and so can’t be put in same taxa

Both are artificial

Monophyletic

Group containing common ancestor and all its descendants

Molecular clock

The regular rate of mutations over time. They’re good for using molecular dating approaches in estimating times of divergence. Calibrate by using known time spans from fossil record

Fossils

Used to calibrate molecular clock but also provide data on character states through time

Croizat’s Panbiogeography

Graphical method of mapping distributions of related organisms and connecting them with “tracks” to find generalized patterns of historical connection. It uses these tracks to make inference on dispersal and vicarience to explain distribution patterns. Main weakness is not being based on phylogenetic hypotheses

Vicariance

The geographical separation of a population, leading to a pair of closely related species

How to infer how geographical shifts have shaped patterns of diversification and vice versa

With phylogeny for reconstruction, mutations to account for the importance of the molecular clock, and calibration with fossil record