Biology (EVO)
Although morphological characteristics are often used to differentiate species what are some drawbacks to this approach?
-Many traits are continuous, such as size and weight -Members of the same species can look different -Different species can look similar
Which of the following examples of morphological traits that can be used to classify organisms as the same species?
Body shape Cell anatomy Sensory structures
Consider a population of sexually reproducing organisms that splits into two or more species. This phenomenon is
Cladogenesis
An evolutionary scientists classified bacteria based on their use of resources and their growth conditions. What type of evidence was used to classify these species?
Ecological factors
Past event in Hox gene evolution with its approximate timing
First Hox gene arose- Over 600 mya First duplication of Hox gene cluster-520 mya Second duplication of Hox gene cluster-420 mya
what is an example of hybrid sterility of postzygotic isolating mechanism?
Mating between a horse and donkey to produce a mule
_____ isolation is a prezygotic isolating mechanism that prevents the exchange of gametes do to morphological features.
Mechanical
Organism characteristics with how they are used to distinguish different species: -Morphological characteristics -Reproductive isolation -Ecological factors -Molecular features -Evolutionary relationships
Morphological characteristics: individuals that have similar physical features are classified to the same species Reproductive isolation:organisms that are unable to produce viable and fertile offsprings are classified to the different species -Ecological factors: organisms that have similar habitat requirements such as temperature rainfall and soil pH or classify to the Molecular features: organisms with similar DNA sequences are considered to be members of the same species Evolutionary relationships: individuals that have descended from the same ancestor are members of the same species
What type of reproductive isolation mechanisms produce infertile hybrids or prevent hybrid Offspring from developing?
Postzygotic isolating mechanisms
Compared to postzygotic isolating mechanisms prezygotic isolating mechanisms are typically more common because
Postzygotic isolating mechanisms use more energy and resources
Which of the following statements is most accurate regarding the relative frequencies prezygotic and postzygotic isolating mechanisms?
Prezygotic isolating mechanisms tend to be MORE common than postzygotic mechanisms.
match each animal with the correct description of its Hox gene Sponge Insect Mammals
Sponge-One Hox Insect- Nine Hox Mammals- Multiple Hox clusters on multiple chromosomes
______ isolation is a prezygotic mechanisms to prevent an inter species hybrids I go up from for me because of breeding for two different species occurs at different times of the day or year.
Temporal
Hox genes affected the development and formation of different body regions by encoding
Transcription factors
The different shapes of the skulls of adult humans and chimpanzees is explained by
heterochrony
What are reproductive isolating mechanisms?
Barriers that prevent successful interbreeding among members of different species
How is speciation hypothesized to be occurring in the apple maggot fly (rhagoletis pomonella)?
Some individuals prefer to feed on hawthorn and others on apple, leading to temporal reproductive isolation.
True or False: morphology may be influenced by genetic variations that influence the relative growth rate of the body during development.
True
Dobzhansky proposed in the 1920s that species are
reproductively isolated from each other
General reasons why organisms often diversify into separate populations that we recognize as species.
-Adaptation to ecological niches results in speciation -An abrupt event causes reproductive isolation
Descriptions that can be used to Define species
-a group of sexually reproducing organisms that can interbreed with each other -a group of organisms that share a distinct set of traits in nature -a group of organisms that share an evolutionary history
True or False: prezygotic isolating mechanisms are less common than postzygotic isolating mechanisms
False
Development biologists have hypothesized that variation in Hox genes may have caused the formation of which of the following?
New body plans
The two main types of reproductive isolating mechanisms.
Postzygotic and Prezygotic isloating mechanisms
two major reasons have been proposed to explain why organisms assemble into different species: 1)Speciation may occur due to abrupt genetic events which can cause reproductive isolation OR 2)Speciation may arise as a consequence of
adaptation to different ecological niches.
All the following are lines of evidence that support the idea that Hox genes number have been instrumental in the evolution and speciation of animals with different body plans except
an arrangement of Hox genes on the chromosome is identical in all animals studied thus far
Scientist compare the DNA sequences of the 16s rRNA gene to distinguish between different species of
bacteria
An increase in Hox genes could enable more complex body forms to evolve because
each gene could become specialized in the region it controls
The ____ species concept defines a species as a group of individuals that have the same set of habitat requirements and influence the environment and other species in a similar way.
ecological
New species can arise due to several factors. These include via natural selection acting on mutations in genes, as well as ____ matings and ___ gene transfer.
interspecies; horizontal
Hybrid ____ serves as a postzygotic isolating mechanism by preventing inter-species hybrid zygote from developing pass early embryonic stages.
inviability
The difference between allopatric and sympatric speciation depends on whether
the populations undergoing speciation live in the same geographic area