Download Hybrids in the Wild Enrichment LESSON 1

Name
Date
Enrichment
Class
LESSON 1
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Hybrids in the Wild
You have learned about hybrids that are
produced when two parents of different
breeds mate. But did you know that
hybrids are also produced when parents
from closely related species, such as a tiger
and a lion, mate? Sometimes animals
produced by these type of interspecies
hybrids cannot reproduce and might not
be as healthy as purebreds.
Scientist Ben Fitzpatrick studies hybrid
salamanders produced from inter-species
crosses. When he first began his field
studies of the salamanders, he expected the
hybrids to be weaker than the purebred
salamanders. To Fitzpatrick’s surprise, the
wild hybrid salamanders were thriving.
“The level of vigor in these hybrids was
completely unexpected,” he said in an
interview with the journal BioMedicine. The
research might have important implications
for endangered species and the
conservationists who work to save them.
The Study
To understand the implications of
Fitzpatrick’s work, it is necessary to go back
to the 1950s, when fishermen in California
began releasing barred tiger salamanders
into ponds and other bodies of water. The
fisherman used salamanders for bait, and
wanted to increase their bait supplies.
Barred tiger salamanders are nonnative
species. Over time, they interacted and
mated with California tiger salamanders,
a native endangered species.
Fitzpatrick and his colleagues compared
the survival rates of three groups of
salamander offspring: pure barred tiger,
pure California tiger, and hybrids of the
two species. They discovered that the
hybrid offspring had higher rates of
survival than either purebred group.
The scientists do not yet know why the
hybrid offspring are thriving. Regardless,
the study predicts that the hybrids will
contribute to the gene pool of the purebred
salamander species now and in the future.
Helping or Hurting Endangered Species?
The California tiger salamander is an
endangered species. If the study’s prediction
is correct, eventually hybrid genes will be
present in all California tiger salamanders.
The native salamanders will survive. But will
they still be considered a separate species?
The question is important in terms of
managing endangered species. The fate of
the California tiger salamanders might lie
in the hands of conservationists. They
might determine that the species is no
longer genetically pure and that the
hybrids are pushing the native purebreds to
extinction. Or they might decide that the
salamanders with hybrid genes represent an
adaptation of the species, allowing it to
thrive in the wild.
Applying Critical-Thinking Skills
Directions: Answer each question or respond to each statement.
1. Infer Why might the hybrid offspring have higher survival rates than the offspring of
the purebred salamanders?
2. Predict what might happen to conservation efforts for the California tiger salamanders
if they are no longer considered to be genetically pure.
Genetics
21