Did the effects of natural selection occur in a lizard population in response to an extreme cold event? During the winter of 2013-2014, southeastern Texas and Oklahoma faced an extreme cold event. In...

Question 2 please: Does natural selection always lead to evolution? Use the information in this activity to answer that question. What more might we need to know to fully answer it?

Extracted text: Did the effects of natural selection occur in a lizard population in response to an extreme cold event? During the winter of 2013-2014, southeastern Texas and Oklahoma faced an extreme cold event. In these areas, the wild populations of the green anole lizard, Anolis carolinensis live naturally. Cold tolerance in this species naturally varies with latitude. Lizards have an internal thermal temperature (called the CTm) at which they cannot function and lose coordination.During the cold weather event, lizards in southernmost Texas (BRO) experienced 28 days below their CTmin, while those in northern Texas (AUS) experienced 8 days. min The researchers hypothesized that the extreme cold may exert natural selection on these populations, eliminating less cold-hardy individuals. They investigated whether survivors of the 2013-2014 winter storms displayed greater cold tolerance than individuals sampled the previous year. They revisited BRO and AUS in April 2014 to measure CTmin of the survivors. Hodgen, OK (HOD) A A BRO 2013-2014 Winter Storms O AUS Arlington TX (ARL) 10 Austin, TX (AUS) Victoria, TX (VIC) Brownsville, TX (BRO) 500 km Summer 2013 Spring 2014 Summer 2014 Figure A (rightmost) shows the critical thermal minimum (CT) for anole lizards from Summer 2013 to Summer 2014. The extreme cold event is designated by "2013-2014 winter storms". The Upper line shows CT for southem lizards (BRO) and the lower line for northern lizards (AUS). Error bars are +/- 1 SEM). Evidence from the study (Figure A - right) showed that BRO populations had a high CTmin before the cold event (CTmn of 10) and the CTmin progressively decreased to 8.8 and 8.5 CTmin in the spring 2014 and summer min min 2014 respectively. The AUS populations showed little change from the initial CTmin value of 8.4 over the year. In summer 2014, both BRO and AUS populations showed relatively the same CTn (8.6). min Critical Themal Minimum (CTmin) (Celsius)


Extracted text: Scientists also looked at the genes that regulate the CT min in anole lizards. They found that the survivors of the cold snap in the BRO location were genetically similar to those in the northernmost population (HOD). GGL Module 16 Module18 F Module 53 35 30- 25- 20- 15에 10어 5- 40- 50 4어 30 3어 20 2어 10- 10- 0- YES YES NO Do BRO survivors show shift towards northern (HOD) expression values? NO YES NO Figures D-F: Bar plots representing the number of genes that shift in expression in the southernmost population (BRO) after the storm in the same direction as gene expression differences between BRO and the northernmost site (HOD). Question 1: Did the effects of natural selection occur in a lizard population in response to an extreme cold event?? CLAIM: EVIDENCE: REASONING: Question 2: Does natural selection always lead to evolution? Use the information in this activity to answer that question. What more might we need to know to fully answer it?