It turns out the humble guppy has a lot to teach us about evolution. They may be tiny but Trinidadian guppies are the rockstars of evolutionary science. They live in steep mountain streams that flow across many waterfalls before they reach the ocean. These waterfalls are important barriers, keeping predators out of parts of the stream.
They may be tiny but Trinidadian guppies are the rockstars of evolutionary science. They live in steep mountain streams that flow across many waterfalls before they reach the ocean. These waterfalls are important barriers, keeping predators out of parts of the stream.
Guppies in places where killifish ate babies evolved in an opposite way – they had fewer, larger babies later in life. It’s a simple experiment but showed that evolution could occur much faster than was previously thought.
A small fish with a big story to tell. They may be tiny but Trinidadian guppies are the rockstars of evolutionary science. They live in steep mountain streams that flow across many waterfalls before they reach the ocean. These waterfalls are important barriers, keeping predators out of parts of the stream.
Researchers found that guppies introduced to a low-predation environment adapted to their new environment by producing larger and fewer offspring with each reproductive cycle. No such adaptation was seen in guppies that colonized a high-predation environment.
Living in the fast lane. Guppies transplanted from this predator-filled pool rapidly evolved to larger sizes. Although natural selection is often viewed as a slow pruning process, a dramatic new field study suggests it can sometimes shape a population as fast as a chain saw can rip through a sapling.
The guppy provides a huge amount of natural variation that can be studied genetically. This variation has not been produced by mutagenesis screens, but instead has been shaped by natural selection.
With each generation, more guppies passed on the gene for small spots to their offspring. The rocks became smaller. With each generation, more guppies with small spots survived long enough to pass on the gene for small spots to their offspring. The rocks became smaller.
Endler's Discovery Endler photographed hundreds of guppies and carefully measured their size, color, and the size and placement of their spots. He began to see a strong correlation between where guppies lived in a particular stream and whether the fish were bright or drab.
We have found that male guppies increased their size at maturity, both length and mass, in response to the non-lethal presence of this predator. This pattern of plasticity is the opposite of that observed in response to reduced food intake, where male guppies reduce size at maturity.
This is sexual selection at work, and it is the force that pushes guppy coloration toward conspicuousness just as hard as predation pushes coloration toward drabness. There may be several evolutionary reasons why female guppies prefer flashy males.
For example, If the upstream pool originally contained no guppies or predators, it is likely that other organisms are also absent. This could mean that there is less competition for food resources in the upstream pools. It seems that increased nutrition could also result in later maturation and increased size.
Wild guppies generally feed on a variety of food sources, including benthic algae and aquatic insect larvae. Guppies are used as a model organism in the fields of ecology, evolution, and behavioural studies....GuppyGenus:PoeciliaSpecies:P. reticulataBinomial namePoecilia reticulata W. Peters, 185914 more rows
Colour patterns of male guppies are considered a classic example of an ornament under opposing selection pressures; sexual selection favours elaborate colours to attract females, but natural selection favours inconspicuous colours to avoid predation [31,33,36,40–44].
Endler's hypothesis was that predators are responsible for much of this variation among populations. He had noticed that guppies sharing their stream with predatory cichlids had fewer spots than guppies living with Rivulus. Cichlids are ravenous predators of adult guppies. Rivulus eat only juvenile guppies.
In the wild, guppies have relatively short generation times (110–210 days [19]) and small body sizes, typically ranging from 15 to 17 mm for male adults and 15 to 30 mm for female adults [20].
A famous experiment by John Endler in 1980 showed that guppies kept in high predation areas developed fewer and duller spots throughout a few generations. And after transferring guppies to low predation areas, over only a few generations, the spots grew more prominent and colorful.
In their experiment, cichlids consistently and preferentially approached, captured, and attacked the brightly colored guppy when confronted with two similarly-sized specimens.