White sharks are one of the most mysterious and fascinating animals in the ocean, but they are also difficult to study and conserve.
One of the challenges that researchers face is determining the sex of white sharks, which is important for understanding their population dynamics, behavior, and reproduction.
Until now, the only reliable way to tell a male from a female white shark was to look for the presence or absence of claspers, which are modified pelvic fins that males use for mating.
However, this method is not always feasible, especially for large and potentially dangerous sharks that are hard to capture or observe closely.
How sexy_markers works
JOSEPH PREZIOSO/AFP via Getty Images
A new study led by CSIRO, Australia's national science agency, has developed a novel bioinformatics tool that can reveal the sex of white sharks based on their DNA.
The tool, called sexy_markers, uses a machine learning approach to identify sex-specific genetic markers from genomic data.
The study, published in the journal Scientific Reports, is the first to report the existence of X and Y sex chromosomes in white sharks, which are similar to those found in humans and other mammals.
The researchers used sexy_markers to analyze the genome sequences of 14 white sharks from Australia and South Africa. They found that white sharks have 41 pairs of chromosomes, including one pair of sex chromosomes.
The sex chromosomes are either XX (female) or XY (male), and they carry genes that determine the sex of the shark.
The researchers identified 148 sex-specific markers, which are regions of DNA that are unique to either the X or the Y chromosome. These markers can be used to distinguish males from females with high accuracy.
The advantage of sexy_markers is that it can work with any type of DNA sample, such as blood, tissue, or saliva. It can also be applied to other shark species, as long as there is enough genomic data available.
The researchers tested the tool on four other shark species: tiger shark, bull shark, whale shark, and leopard shark. They found that all of them have sex chromosomes, but with different numbers and types of markers.
The tool is also fast and easy to use, as it only requires a few steps and a standard computer. The researchers have made it freely available online so that anyone can use it to sex sharks or other animals with sex chromosomes.
The ability to determine the sex of white sharks and other sharks is crucial for conservation and management purposes.
For example, knowing the sex ratio of a population can help estimate its reproductive potential and genetic diversity. It can also help identify potential mating areas and migration patterns.
Furthermore, knowing the sex of individual sharks can help monitor their growth, health, and movements over time.
The researchers hope that sexy_markers will be a valuable tool for shark researchers and managers around the world, as well as for the public who are interested in learning more about these amazing animals.
They also hope that the tool will inspire more genomic studies on sharks, which can reveal new insights into their evolution, ecology, and physiology.
