BIOS 230: Homework 2

BioS 230 Homework 2 Instructions: 1. Please write/type out your answers using different color (e.g. blue/red) in this document or in a separate paper. Make sure TA is able to read your handwriting! 2. Click on the "Gradescope-Homework"on Blackboard, it will bring you to the Gradescope platform. Submit your assignment in PDF, JPG, or PNG format. Gradescope does not accept Word document. 3. Two ways to submit assignment: a) Save your answers for each question in a separate file; b) Submit your answers in a single pdf file and select the pages corresponding to each question. Make sure you assign the correct page number to your questions, or else your answers will not appear on the grading platform. Notes: Check and make sure you upload the right answer for each question. 1. (5 pts) Resplendent quetzal (Pharomachrus mocinno) is a beautiful bird species that lives in the tropical forests of Central America. Assuming that you would like to breed resplendent quetzal to produce shorter tails. You measured 50 resplendent quetzals and obtained a mean tail length of 80.4 cm. You selected 10 resplendent quetzals with shortest tails as breeders. The mean tail length of the breeders is 74.2 cm. After mating, offspring of the resplendent quetzal breeders have a mean tail length of 76.8 cm. What is the heritability of tail length in this resplendent quetzal population? Show your work and round numbers to 2 decimal places. Note: Selection differential (S) will be negative value if selection favors lower values of a trait, which would result in negative response to selection (R). 4 80.4cm 24.29 6 km 3.6cm Ya 80 R 76.8cm 2 am he r 3 6 h Rsh 0.58064516129 h 1 0 58064516129142 0.53064516129 h 0.58 Answer 0.58 1 2. (7 pts) Construct a cladogram to demonstrate the evolutionary relationships of five species based on the characteristics presented in the table below. The column that has “X” indicates the organism has that particular characteristic. Label the derived traits on the cladogram. Character Four limbs Feathers Eggs with shells Bony skeleton Fur Vertebrae Bird X X X X X Human X X X X Snake X Shark X X X Bony fish X X X news df.hn short or bird 2 3. (13 pts) You are a paleontologist attempted to reconstruct a phylogeny for 8 species (A-H) based on the fossil skull specimens. You have collected and measured morphological characteristics for each skull specimen, summarized in the table below. Data do not reflect the evolution of currently living organisms. Species A B C D E F G H (Outgroup) 1 (teeth) 16 18 18 18 18 18 22 2 (canine) N N N N N N P 3 (brow) N N Y Y Y Y N 22 W Y 4 5 (diastema) (mandible) Y O Y O Y O N O N R N R N R N R 6 (nose) Y Y Y Y N N Y 7 (eye) C C C C C C C 8 (crest) N N N N Y Y Y Y E Y Descriptions for each morphological characteristic: Character #1 = Number of teeth on the maxilla (upper jaw) Character #2 = Presence of canine (W = well developed, P = partially developed, or N = no) Character #3 = Presence of brow ridge (Y = yes, or N = no) Character #4 = Presence of diastema (Y = yes, or N = no) Character #5 = Mandible shape (O = oval shape, R = rectangle shape) Character #6 = Presence of nasal conchae (Y = yes, or N = no) Character #7 = Eye sockets (E = open eye sockets, C = closed eye sockets) Character #8 = Presence of medial cranial crest (Y = yes, or N = no) Here are mammal skull images that display some of the characters listed in the table. Note: The images provided are to help you envision how morphological data were collected. You do not have to know the locations of the structures to construct the phylogeny. 3 Phylogeny Reconstruction Use the cladogram below, label the species (A-H) at the appropriate terminal nodes (tips). Identify the synapomorphies (shared derived characters) and autapomorphies (unique derived characters to a given taxon), Characters# 1-8, on the cladogram. The locations of the derived characters have been designated with the “tick marks”. The placement of the outgroup species H and the first synapomorphy (Character #7) have been provided for you. Instructions for Phylogeny Reconstruction 1. Look at the morphological data listed in the table. Start with Character #7. Species A-G have closed eye sockets (C). Species H has open eye socket (E), suggesting that open eye socket is an ancestral trait. Label 7(C) at the first “tick mark” to indicate all the descendant taxa after this point have closed eye sockets. From there, the placement of the species H can be determined. The placements of species H and the first syapomorphy 7(C) have been provided to you. 4 2. Look at Character #2. Species A-F do not have canine. Species G has a partially developed canine. Species G has a morphological character more similar to the outgroup species H than other taxa. With this information, label derived characters 2(N) and 2(P) at the corresponding tick marks on the cladogram. 3. You should be able to place species G on the terminal node (tip), and label another autapomorphy that separates species G from species H. When there are two derived characters on the same branch, since we do not have sufficient information to determine which trait evolved first, you don’t have to worry about the order of the derived characters. 4. Next, look at Character #6. Species E and F are the only two species without nasal conchae. Label synapomorphy 6(N) on the branch and determine the proper placements for species E and F. 5. Proceed with Characters #5, #8, and #4 (in this order). Place the derived characters on the cladogram following the morphological character descriptions in the table, e.g. 5(O) or 5(R). Identify the terminal nodes (tips) for other species. 6. Place the last two Characters #1 and #3 on the cladogram. 7. At this point, you should have all the species (A-H) and derived characters (Characters #1-8) properly placed on the cladogram. Do a final check on your phylogeny to make sure you obtain the derived characters listed in the table for each species. 8. You have successfully reconstructed a phylogeny! 5 I f if IN