All About Inbreeding: Molecules Make a Difference

Oswaldo Diaz

A single hair can tell us about a species’ past, future and how science could help prevent its extinction.

This was the point made by Maria Kretzmann, a Glendale College biology instructor, at the May 25 science lecture, “The Use of Molecular Tools in Conservation Biology.”

Kretzmann lectured on the advantages that molecular tools offer by providing scientists with information about the DNA and genetic makeup of living organisms.
Molecular biology is the study of the structure, function and makeup of important molecules such as DNA, RNA and proteins.

Partnered with existing methods of animal conservation and the protection of endangered species, molecular biology offers scientists a detailed view into what drives a species to extinction and how it can be prevented.

There are five key components in which scientists use molecular biology to aid endangered species.

The first, functional diversity, analyzes ecological interactions such as among species. “Tasmanian Devil populations have dropped a staggering 70 percent since 1996 because a form of contagious cancer has spread throughout the population,” Kretzmann said.

After analyzing the genetic makeup of afflicted Tasmanian Devils and comparing it to individuals who are immune to it, scientists have been able to discover that the animals with higher genetic variation are, in most cases, the ones that display an immunity to the cancer.

The genetic variations are present in the major histocompatibility complex which is a gene-dense region of the mammalian genome that plays an important role in the immune system and autoimmunity.

The second, population structure, provides insights into evolutionary processes and helps identify groups of individuals by their genetic makeup. A common practice in wildlife conservation is the use of tracking devices to follow migration patterns and analyze population sizes. Molecular biology adds an insightful layer to this practice by taking genetic samples from monitored individuals to create a form of genetic tracking for certain species.

One of the drawbacks of migration tracking when analyzing population structures for wildlife conservation is that it merely demonstrates the movement of species but does not reveal whether a species is reproducing and at what rate.

“Just because they move does not mean they are breeding,” said Kretzmann. By genetically tracking individuals, scientists can determine breeding patterns by the amount of variation in the genetic makeup of individuals. The presence of higher variation levels suggest that individuals are mating outside circles of inbreeding and therefor achieving a diverse genetic makeup that could benefit the species as these variations make them more resistant to environmental changes and disease.

The third, forensic identification, is used in identifying specific individuals by breaking down their genetic makeup.

Advancements in this area have prompted scientists to create the “Bar-code of Life” which aims to develop a mechanism capable of generating a unique genetic bar-code for every species of life on earth.

Meanwhile, with the help molecular tools scientists were able to uncover the Japanese whaling scandal. After analyzing meat samples taken from a bush meat market in Japan, with the help of forensic identification, scientist were able to discover that the meat being sold was Blue Whale along with other rare whale species. This violated the 1986 IWC moratorium that condones whale hunting for scientific but not for commercial purposes.

The fourth, kinship, uses molecular tools to analyze the individuals in captive mating programs in order to maximize genetic diversity and avoid inbreeding.

To ensure the survival of their offspring female chimpanzees mate promiscuously to trick male chimps into believing they are the fathers of the newborns. Scientists then compare the DNA of the infant and the mother with possible fathers to determine if a dominant male is fathering most of the offspring.

“If this is the case the dominant male is either castrated or relocated in order to allow for different males to mate and provide the Chimpanzee population with a higher genetic variation,” Kretzmann added. With a higher variation these chimps can better adapt to changing environments and built a stronger immune system.

The fifth, hybridization, examines the process of combining different varieties of species and organisms to create a hybrid. With the use of molecular tools scientists have been able to identify certain species such as the red wolf, a cross between a gray wolf and coyote, as hybrids. Population numbers for the Florida panther were so low that in order to promote a large, healthy and genetically diverse group a slightly different kind of panther was introduced from Texas to mate with Florida panthers to create a hybrid animal in order to save the species from extinction.

While inbreeding may be counter beneficial to a population in the long run, breeding species that are too genetically different has a major drawback, outbreeding depression. This occurs when offspring from crosses between different populations have lower fitness than offspring from crosses between the same population.

“I had no idea of the extremes scientists go to in order to save animal species,” said student Michelle Acuña.

The work that is being done behind the scenes by genetic scientists in the conservation of endangered species often goes unnoticed by the general public. However, after a highly informative lecture, Kretzmann was able to convey the challenges and wonders of the use of molecular tools in conservation biology.

For more information about the lecture and related topics contact Maria Kretzmann at (818) 240-1000 ext. 5363.