Untitled Flashcards Set

• What are fossil “strata” and by what mechanisms do geologists suggest that they  formed? What aspects of the fossils found in strata have been suggested to be evidence of evolutionary change?

Fossil strata are layers of sedimentary rock that contain fossils. The sediment builds up layer by layer over long periods of time. In the layers, fossils are trapped, and changes can be observed from fossil to fossil based on their position in the sediment.

• Using potassium-40 as an example, describe how radiometric dating works to allow scientists to estimate the age of fossil layers. What is the “half-life” of a radioactive element, and why is this property important in radiometric dating?

Radiometric dating allows scientists to observe the estimated age of whatever they are viewing based on how much the “subject” contains of certain isotopes. These isotopes have “half-lives” which basically means that each isotope decays over time. A “half-life” is a unit of measurement based on how long it takes for the isotope to decrease by half. So scientists can use the estimated “half-life” of an isotope to determine the age of fossil layers

• Define the terms “Cambrian Explosion” and “Punctuated Equilibrium,” and describe how they’re connected.

The Cambrian Explosion was an event that took place 530 million years ago in which many new animal forms appeared. Punctuated equilibrium is the concept that evolution of new species’ arise very suddenly in the fossil record, followed by a long period of time before the next rapid induction of species. The Cambrian Explosion is theorized to be an example of punctuated equilibrium in which many new animal forms arose during the time period. 

• What were Darwin’s five premises, and how did they shape his theory of evolution?

-Overpopulation of organisms. Population growth would be exponential if all species survived and reproduced. 

- Resource Limitation. There is a limited amount of resources on Earth, which induces competition. Too many living things and not enough resources for all of them. 

- Population Stability. Populations tend to remain stable over time because of the struggle for survival. 

- Variation of Traits. Variance exists between species of organisms and this variance brings about certain traits that are either advantageous or disadvantageous. 

- Heritability of Traits. Variance between organisms is heritable. There is clear genetic heritance between generations of the variance from species to species.  

• Describe how Darwin’s finches in South America have been proposed to illustrate the concept of adaptive radiation.

• Darwins finches in South america are the perfect example of adaptive radiation. Darwin observed differences in finches from island to island in South America. He observed differences in the beak types, which showed that each species of finch had adapted to the conditions on their particular island to obtain food, and to have advantageous traits for their habitat. 

• Identify and describe three distinctive types/categories of homology.

• Genetic homology - Similarities between DNA or amino acid sequences between organisms due to a common ancestor. 

• Anatomical homology - Similarities in anatomical structures due to inheritance from a common ancestor. 

• Developmental - Similarities between the development of embryos between different species that share to a common ancestor. 

• Identify and describe two (of the four) biological species concepts discussed in class.  Describe drawbacks/limitations of each.

• Ecological species concept - Definition of species based on ecological niche, how they interact with the living and nonliving parts of their environment. Effect and role on the ecosystem. 

• Drawbacks - how is the ecological niche understood?

• Morphological species concept- Characterizes a species based on structures and body shape.  

• How many traits included in analysis? How much variance is permitted?