The body weight of offspring of bird species is range between 12 gm to 18 gm. In a laboratory experiment, species was subjected to selection pressure having influence on the offspring body weight. After many generations of experimental selection pressure, the body weight range between 14 gm to 16 gm. Which of the following natural selection operate on this species?

#Question id: 8782

#Unit 9. Diversity of Life Forms

A phylogenetic tree is shown for the three domains of life (Eukarya, Archaea, and Bacteria). The tree branches in two directions from the first point, labeled Common ancestor of all life. One branch leads in the direction of Eukarya and Archaea, and the other branch leads to Bacteria. The branch leading to Eukarya and Archaea divide, one branch leading to each domain. The branch leading to Eukarya divides into four branches. One leads to Euglenozoans, and the other three lead to branching points. The first leads to Forams in one direction, and another branching point in the other that leads to Diatoms and Ciliates. The second branching point leads to Red algae in one direction, and a branching point that leads to green algae and land plants in the other direction. The third branching point leads to amoebas in one direction, and a branching point that leads to fungi and animals in the other direction. Land plants, Fungi and Animals are all highlighted.

Cyanobacteria were once called blue-green algae because they are photosynthetic. According to the phylogeny shown, the cyanobacteria are more closely related to gram-positive bacteria than to ________.

#Question id: 8783

#Unit 9. Diversity of Life Forms

Which of the following statements is accurate, at least according to our present knowledge?

#Question id: 8787

#Unit 9. Diversity of Life Forms

Which of the following statements is accurate, at least according to our present knowledge?

#Question id: 8788

#Unit 9. Diversity of Life Forms

A phylogenetic tree is shown for the three domains of life (Eukarya, Archaea, and Bacteria). The tree branches in two directions from the first point, labeled Common ancestor of all life. One branch leads in the direction of Eukarya and Archaea, and the other branch leads to Bacteria. The branch leading to Eukarya and Archaea divide, one branch leading to each domain. The branch leading to Eukarya divides into four branches. One leads to Euglenozoans, and the other three lead to branching points. The first leads to Forams in one direction, and another branching point in the other that leads to Diatoms and Ciliates. The second branching point leads to Red algae in one direction, and a branching point that leads to green algae and land plants in the other direction. The third branching point leads to amoebas in one direction, and a branching point that leads to fungi and animals in the other direction. Land plants, Fungi and Animals are all highlighted.

Examine the figure. If you were a graduate student trying to develop a thesis project that would resolve polytomies, which of the following groups would you study?

#Question id: 8789

#Unit 9. Diversity of Life Forms

If additional DNA sequence evidence shows that yeast genes for synthesizing proteins are more similar to protein-synthesizing genes in bacteria than those in archaea, a modern systematist would ________.

#Question id: 8840

#Unit 9. Diversity of Life Forms

There are at least a dozen known species in the extinct genus Lystrosaurus. If each species was suited to a quite different environment, then this relatively large number of species is likely due to