8.2 Speciation Flashcards
What is the biological species concept?
states that a species is a population or group of populations whose members have the ability to breed with one another in nature and produce fertile offspring
Limitations for the biological species concept
-Asexually reproducing organisms NOT included
-Fossils & extinct animals are not alive, so NOT included
Morphological species concept
-Organisms are classified on their appearance (internal and external structures)
-Easy to use, extremely helpful in communicating characteristics, behaviour and relationships of organisms
Limitations of morphological species concept
does NOT account for the reproductive compatibility of organisms of the same species which look different
Example of morphological species concept
E.g. Red-shaft flicker lives in western North America, the yellow-shaft flicker lives in the East, and where their ranges overlap they interbreed to produce an offspring that doesn’t look like either parent (hybrid)
What is a hybrid?
Offspring resulting from the mating of individuals of 2 different species
-e.g. mule (donkey + horse) or liger (lion + tiger)
What is the modern species concept?
-Includes BOTH the morphological and biological species concepts
-Important in evolution because it recognizes that individuals pass genes to the next generation
-Allows scientists to classify organisms and study how they change over time
Microevolution definition
Microevolution explains how populations evolve (change in allele frequencies)
Macroevolution definition
Macroevolution refers to more dramatic biological changes
-Origins of different species
-Extinction
-Evolution of major new features (e.g. wings or flowers)
What is speciation
Speciation – origin of new species
-leads to an increase in diversity
Which type of selection would be an example of speciation?
disruptive selection would be an example of speciation
What is reproductive isolation/barriers?
The inability of two organisms to reproduce due to some kind of physical or behavioural barrier
Geographic isolation
Earth constantly changes due to plate tectonics
-Can physically separate populations
-e.x. creation of a canyon, an area floods to create an island, a sidewalk is built in a forest where snails frequent
What are splinter populations?
-The separation of a small “splinter” population from its main population is a crucial event in the origin of species.
-Once separate, the splinter population may follow its own evolutionary course.
-Changes in the allele frequencies caused by genetic drift and natural selection can accumulate in the splinter population, making it less and less like the main population
(e.g. Australia and its marsupials)
Habitat Isolation
-When organisms adapt to different niches in the same area yet cannot interbreed
-e.x. Stickle back fish in various BC lakes where some feed on the bottom and others in open water
-e.x. Oak trees—some thrive in sandy soil, others loamy soil
-e.x. Various lizards live in different levels of the canopy
Temporal Isolation
Different breeding periods
-e.x. Western Spotted vs. Eastern Skunks breed in fall vs. winter
Behavioural Isolation
Different courtship behaviours prevent mating
-e.x. Eastern and Western Meadow Larks have different calls yet near identical plumage
Mechanical Isolation
Incompatible reproductive structures
-e.x. Bradybaena species of snails have genital openings that differ in shape
Gametic Isolation
Sperm and eggs have molecular markers or proteins that are incompatible
-e.x. Fish sperm (and eggs) released into the water
Hybrid Inviability
Usually dies during fetal development; typically unhealthy
-e.x. Ensatina salamanders