Chapter 23 Flashcards
half-life
The time it takes for half of a given amount of a radioisotope to decay
radiometric dating
A dating method that uses measurements of certain radioactive isotopes to calculate the absolute ages in years of rocks and minerals
plate tectonics
The geological theory describing how Earth’s crust is broken into irregularly shaped plates of rocks that float on its semisolid mantle
continental drift
The long-term movement of continents as a result of plate tectonics
continuous distribution
A geographical distribution in which a species lives in suitable habitats throughout a geographical area
disjunct distributions
A geographical distributions in which populations of the same species or closely related species live in widely separated locations
Dispersal
The movement of organisms away from their place of origin
Vicariance
The fragmentation of a continuous geographical distribution by nonbiological factors
biotas
The total collection of organisms in a geographical region
biogeographical realms
A major region of Earth that is occupied by distinct evolutionary lineages of plants and animals
endemic species
A species that occurs in only one place on Earth
convergent evolution
The evolution of similar adaptations in distantly related organisms that occupy similar environments
biodiversity
The richness of living systems as reflected in genetic variability within and among species, the number of species living on Earth, and the variety of communities and ecosystems
adaptive radiation
A cluster of closely related species that are each adaptively specialized to a specific habitat or food source
adaptive zone
An environment or part of an environment that may be occupied by a group of species exploiting resources in a similar manner
extinction
The death of the last individual in a species or the last species in a lineage
background extinction rate
The average rate of extinction of taxa through time
mass extinctions
The disappearance of a large number of species in a relatively short period of geological time
phyletic gradualism hypothesis
The hypothesis that most morphological change occurs gradually over long periods of time
punctuated equilibrium hypothesis
The evolutionary hypothesis that most morphological variation arises rapidly during speciation events in isolated populations at the edge of a species’ geographical distribution
paedomorphosis
“child” “form/shape”
A common form of heterochrony in which juvenile characteristics are retained in a reproductive adult
exaptation (preadaptation)
A trait that is adaptive in a context different from the context in which it originally evolved
evolutionary development biology
A field of biology that compares the genes controlling the developmental processes of different animals to determine the evolutionary origin of morphological novelties and developmental processes
homeotic genes
Any of the family genes that determines overall body plan (the structure of body parts) during embryonic development
23.1
- Fossils are the parts of organisms preserved in sedimentary rocks or in oxygen-poor environments
- The fossil record is incomplete because few organisms fossilize completely, because some organisms are more likely to fossilize than others, and because natural processes destroy many fossils
- Fossils provide a relative dating system, the geological time scale, for the strata in which they occur. Radiometric dating techniques establish the absolute age of rocks and fossils
- The fossil record provides data on change in morphology, biogeography, ecology, and the behavior of organisms
What biological materials are the most likely to fossilize?
Hard parts, such as the shells or bones of animals, are the materials most likely to fossilize
Why does the fossil record provide an incomplete portrait of life in the past?
The fossil record provides an incomplete portrait of life in the past because not all organisms are equally likely to form fossils; fossils do not form in all types of habitats; and fossils are often destroyed by processes and erosion
What sorts of information can paleobiologist discern from the fossil record?
The fossil record provides information about the morphology of ancient organisms; how structures changed over time; and the proliferation and extinction of evolutionary lineages. It also offers indirect evidence about the behavior, ecology, and physiology of organisms that lived in the past.
How did continental drift affect the geographical distribution of organisms?
Continental drift caused large-scale geographical separation of populations and lineages that subsequently evolved in isolation
What effect glaciations have on sea level?
Sea levels fell whenever a large proportion of Earth’s water was incorporated into glaciers
Which type of geographical distribution requires no special explanation?
Continuous distribution requires no special explanations. Biologists infer that lineages with a continuous distribution simply occupy all or one part of their historical range
Why do distantly related species that live in different biogeographical realms sometimes resemble each other?
Distantly related species that live in widely separated parts of the world may resemble each other because convergent evolution fosters similar adaptations to the environments they occupy.
What factors might allow a population of organisms to occupy a new adaptive zone?
A population of organisms may occupy a new adaptive zone after the evolution of a key morphological innovation that allows it to use the environment in a unique way or after a once-successful group of organisms declines.
What events apparently triggered the mass extinction at the end of the Permian period?
Huge volcanic eruptions triggered a chain of events that led to the mass extinction at the Permian period. These eruptions warmed the atmosphere and oceans enough to melt frozen undersea methane reserves. The methane entering the atmosphere warmed the climate even further, creating a “runaway greenhouse” effect.
When did the first major adaptive radiation of animals occur?
The first major adaptive radiation of animals took place in the Cambrian era.
Did the horse lineage undergo a steady increase in body size over its evolutionary history?
The horse lineage was highly branched, and it included some species that were larger and some that were smaller than their ancestors.
What is the difference between the morphological change predicted by the phyletic gradualism hypothesis and the punctuated equilibrium hypothesis?
Phyletic gradualism predicts that morphological change is slow and steady, producing fossils with morphologies that are intermediate between the structures found in lower and higher strata. The punctuated equilibrium hypothesis predicts that the morphological changes occur rapidly as new species form and that most species experience little morphological change for long periods of time.
What is the difference between allometry and heterochrony?
allometry refers to the differential growth of body parts. Heterochrony refers to changes in the timing of developmental events.
What evidence suggests that many developmental control genes have been conserved by evolution?
Similar developmental control genes are present in a wide variety of animals, plants fungi, and prokaryotes. Their widespread distribution suggests that they were present in the ancestor of all these organisms and have been conserved through countless generations.
What genetic factor is apparently responsible for the presence or absence of spines in stickleback fist?
The Pitx1 gene is expressed in fin buds that later produce spines, and it is not expressed in those that fail to produce spines.
23.2
- Earth’s crust is composed of plates of solid rock that float on semisold mantle. New crust is constantly generated and old crust is recycled. Currents in the mantle cause the continents to move over geological time. The breakup of the continents profoundly influenced biological evolution by separating populations and creating more shallow marine habitat
- Continental movements caused variations in climate, the extent of glaciations, and sea levels. Asteroid impacts and volcanic eruptions have also influenced Earth’s environment, sometimes triggering large-scale extinctions.
23.3
- Disjunct distributions of species can be produced by dispersal and/or Vicariance. Dispersal results in a disjunct distribution when a new population is established on the far side of a barrier. Vicariance results in a disjunct distribution when external factors such as continental drift fragment the landscape.
- Continental drift has created six major biogeographical realm, each with a character biota.
- convergent evolution produces similar adaptations in distantly related species that live in similar environments.
23.4
- adaptive radiation produces morphological diverse species within lineages increasing biodiversity.
- extinction decreases species diversity. mass extinctions have occurred at least five times in the history of life. tectonic activity, climate change, and asteroid strikes are probable causes of mass extinction
- biodiversity has increased repeatedly since life first evolved, partly in response to increased geographical separation of the continents and partly because complex interactions evolve among existing species.
23.5
the horse lineage is complex and highly branched. It includes species of various sizes and diverse morphological adaptations
-the tempo of morphological change varies among lineages. some exhibit a pattern of gradual change through time. other lineages confirm the predictions of the punctuated equilibrium hypothesis
23.6
- morphological novelties can arise from evolutionary changes in the relative growth rates of body parts or in the timing of developmental events
- evolutionary developmental biology-evo devo-examines how evolutionary changes in genes that regulate embryonic development can foster changes in body shape and form
