This week we are bringing you something a little different – a ‘conservation conversation’. Something to get you thinking and conversing with those around you about some serious conservation issues we are facing. READ, THINK, CONVERSE & LEARN!
Whether we like it or not, human activities have affected natural habitats in every continent and every climatic zone, with the most transformed of areas having absolutely no undisturbed ecosystems remaining. How humans are changing landscapes has been a topic of study for centuries, but has become even more relevant in the last few decades. How animals are then adapting to this change is vital for assessing the overall impact on biodiversity.
Humans are changing landscapes in various ways but have had the biggest impact on visual and acoustic landscapes. Visual environments are changing due to the addition of anthropogenic substances into river systems which dirty the water, habitat destruction and most significant; light pollution. Male fish are adapting to these changes by putting less effort into displaying for females in areas where the water has been clouded because the females are almost “guessing” who the higher quality male is. Anthropogenic lighting means that from an ecological point of view, some animals are effectively exposed to a 24 hour day.
Birds are adapting to this change by starting their calling behaviour earlier both at a seasonal and daily scale. Insects are inherently attracted to light and are therefore often plentiful around light sources. Some migratory bird species have figured this out and are no longer forced into migrating from Europe in the winter due to food shortages but are choosing to spend their time in artificially lit areas instead.
Acoustic environments have been altered by humans to be on average noisier than natural areas, with low-frequency sounds such as those created by big engines dominating. This is a problem as many animals communicate with low-frequency sounds, so the louder, artificially generated noises are masking those produced by animals, resulting in break downs in communication. Animals of both the land and sea are responding to reduce the masking of these anthropogenic sounds by increasing both frequency and amplitude of their vocal communications. However, some species have not the physiological capacity to incorporate complex sounds or increase frequency and amplitude of call in response to anthropogenic noise which has resulted in the decreased perception of alarm calls and those involved in group cohesion in squirrels.
In conclusion, species that are able to rapidly adapt their communication systems to anthropogenic change are likely to undergo speciation. With slight changes in visual and acoustic signals in response to manipulated environments resulting in slightly different selection pressures which may ultimately lead to individuals from anthropogenic environments producing signals that are unrecognisable to individuals from natural areas and therefore lead to communicative exclusion and two separate species. However, those species that do not have plastic adaptability in their communication signals may be greatly negatively affected by anthropogenic changes to chemical and acoustic environments which may hinder reproduction, group cohesion and escape from predation and ultimately lead to species extinction. Both speciation and extinction can have serious consequences for ecosystem functioning and community structuring and the long-term impacts of anthropogenic changes to the communication process in animals could be far more severe than what we are currently observing.
Written by Dean Carlisle
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