Tony
anutej_at_loxinfo.co.th
Edward Venn wrote:
> >>I have a question I would like to ask the group about species >>and
> >>niches. Basically what I have on my mind is this, In any
> >>given habitat is species diversity limited by ecological niches or by the
> >>ability of the genera that lives there to adapt to available niches? Or is
> >>the number of occupied niches a factor of time between catastrophic events
> >>that wipe the slate clean or at least cut down on species? I ask this
> >>because of the differences in fish populations in different areas of the
> >>globe. It seems that in some areas niches are filled that are >>blank in
> >>other areas. Any one have comments on this?
>
> The evidence seems to point to this, I also think that man has had an effect
> on the fish in Asia as 4,000 years of paddy culture has caused the evolution
> of rice and also selected for species of fish, crustaceans and plants that
> can benefit from this environment and the conditions it creates. As
> excellent examples I give the Oryzias group which are egg hangers. They
> usually mate and then choose a location to hang their eggs that has a stable
> water level and temperature. This group of fish are found throughout SE Asia
> and the Indian subcontinent. In Japan they actually are in decline in areas
> without rice culture. Likewise the gouramie complex in Asia. These fish also
> thrive in paddies and have an extra breathing apparatus that allows them to
> survive in oxygen poor environments. Recent research also points to the
> construction of bubblenests as a temperature modulation device. The bubbles
> actually break up and refract the sun's rays.
>
> Edward Venn
> Tokyo Japan
>
> ______
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