Ch 24 Flashcards
(28 cards)
Speciation is the beginning of ___________ change.
Speciation marks the start of large-scale evolutionary changes (macroevolutionary change).
Effect of geographic barriers on species
Species unable to cross barriers may undergo speciation, while those that can cross remain a single population. Example: Speciation in squirrels when the Grand Canyon formed versus no speciation in the birds that lived there since they could fly across the canyon
Natural Selection and Finch Evolution
The diagram illustrates how natural selection can lead to the evolution of different species from a common ancestor, such as finches with different feeding habits.
Niche
The particular area within a habitat occupied by an organism (what an organism eats, does, and where it lives).
Example of Hawaiian honeycreepers as adaptive radiation
From a single finch-like ancestor, over 40 species have evolved on the islands. Variation in color and bill shape is related to their habitat and diet.
Definition of Reproductive Isolation
Barriers that prevent members of two species from producing viable, fertile hybrids.
Speciation
Speciation is the process by which new distinct species evolve.
Adaptive Radiation
The divergence of many adapted species from a single common ancestor after being introduced to new environments.
Geographic isolation
Occurs when a physical barrier divides a population, preventing interbreeding and leading to speciation.
Evolution is NOT goal oriented
Mutations are random
Importance of Reproductive Compatibility
Members of a biological species are united by being reproductively compatible.
Cumulative change during many speciation episodes accounts for sweeping evolutionary change.
Over time, multiple speciation events lead to significant evolutionary transformations.
Speciation in the Grand Canyon
Two separate squirrel species now inhabit the north and south rims due to speciation caused by geographic isolation.
Environmental Influence
Different environments lead to different variations being selected for.
Pacing of Speciation
Speciation often occurs slowly/ gradually, with populations developing increasingly distinct traits.
Microevolution
The change in the genetic makeup of a population from generation to generation.
What does a node represent on a Phylogenetic Tree?
common ancestor shared between all organisms above that node
Evolution is a branching tree
Evolution is not a ladder of progress, it is a branching tree of differences.
Biological Species Definition
A population, or group of populations, whose members can interbreed in nature and produce viable, fertile offspring, but cannot produce viable, fertile offspring with members of other populations.
Macroevolution
Macroevolution is the result of processes like mutation, gene flow, genetic drift, and natural selection over 3.8 billion years.
How mutations lead to reproductive isolation
Mutations can lead to a change in courtship rituals or breeding times.
The process by which organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes new resources available (new niches available).
Adaptive radiation
Example of a geographic barrier leading to reproductive isolation
a valley, canyon, mountain range, or river that divides a population into two subpopulations
Cause of speciation
Speciation occurs when members of a species become reproductively isolated, leading to very little to no gene flow between two populations. Mutations may occur that prevent individuals from producing viable, fertile offspring.
