Question

sexing turtles - \hot chicks and cool dudes\ - cer
on average, each sea turtle nest contains 100 eggs. the female digs a nest to a depth of 46 - 56 cm (18 - 22 inches) and deposits the eggs. there is a natural temperature gradient that occurs within the nest. the eggs at the upper range of temperature (29c) produce females. eggs at the lower range produce males.
the data shows green turtle eggs hatched in two locations in australia at the great barrier reef. australia is in the southern hemisphere. the northern beach locations are closer to the equator and have warmer temperatures than the southern locations.
examine the graph showing the percentages of females hatched at each location the upper graph summarizes the proportions of females (gray) and males (black) in each life - stage class for the northern gbr population. the lower graph shows similar data for the southern gbr population.
source: doi: 10.1093/icb/icaa044

1. what determines the sex of hatchling sea turtles?
2. the data shows two hatching sites in australia. how does the location of the sites influence the temperature of the nests?
3. based on the data, what claim can be made about the sex ratios of turtles at the two locations?
4. summarize the evidence from the graphs that support the claim.
5. how does this study connect to the broader issue of climate change? (reasoning)
6. how could the data from this study be used to protect endangered turtle populations?

Explanation:

Step1: Identify sex - determining factor

The sex of hatchling sea turtles is determined by the temperature of the nest during incubation. Eggs at higher temperatures (around 29°C) produce females, while eggs at lower temperatures produce males.

Step2: Analyze location - temperature relationship

The Northern beach locations in Australia are closer to the equator and have warmer temperatures than the southern locations. Warmer nests (in the north) are likely to produce more females, and cooler nests (in the south) are likely to produce more males.

Step3: Make a claim about sex - ratios

The Northern GBR population is likely to have a higher proportion of females, especially in the warmer life - stage classes (juveniles, sub - adults, adults), compared to the Southern GBR population. The Southern GBR population is likely to have a more balanced sex - ratio or a higher proportion of males.

Step4: Summarize evidence from graphs

The upper graph for the Northern GBR population shows a high percentage of females across life - stage classes (gray bars are dominant). The lower graph for the Southern GBR population shows a more even distribution of males and females across life - stage classes.

Step5: Connect to climate change

Climate change is causing an increase in global temperatures. Since sea turtle sex is temperature - dependent, rising temperatures could lead to a significant shift in sea turtle sex - ratios towards more females. This could have long - term consequences for the genetic diversity and reproductive success of sea turtle populations.

Step6: Suggest data usage for protection

The data could be used to identify critical nesting areas that are likely to be most affected by temperature changes. Conservation efforts could then focus on these areas, such as creating shaded areas to lower nest temperatures or relocating nests to cooler areas to maintain a more balanced sex - ratio.

Answer:

1. The temperature of the nest during incubation determines the sex of hatchling sea turtles. Eggs at higher temperatures (around 29°C) produce females, and eggs at lower temperatures produce males.
2. The Northern beach locations are closer to the equator and have warmer temperatures than the southern locations. Warmer nests in the north are likely to produce more females, and cooler nests in the south are likely to produce more males.
3. The Northern GBR population is likely to have a higher proportion of females, especially in the warmer life - stage classes, compared to the Southern GBR population which is likely to have a more balanced sex - ratio or a higher proportion of males.
4. The upper graph for the Northern GBR population shows a high percentage of females across life - stage classes. The lower graph for the Southern GBR population shows a more even distribution of males and females across life - stage classes.
5. Climate change is causing rising temperatures. Since sea turtle sex is temperature - dependent, rising temperatures could lead to a significant shift in sea turtle sex - ratios towards more females, which could impact genetic diversity and reproductive success.
6. The data could be used to identify critical nesting areas most affected by temperature changes. Conservation efforts could focus on these areas, such as creating shaded areas or relocating nests to maintain a more balanced sex - ratio.