Diving animals like penguins, puffins, and cormorants may be more prone to extinction than non-diving birds, according to a new study by the Milner Centre for Evolution at the University of Bath.
According to the scientists, this is because they are highly specialized and so less able to adjust to changing circumstances than other birds.
Diving birds are more prone to extinction
PASCAL POCHARD-CASABIANCA/AFP via Getty Images
The capacity to dive is relatively unusual in birds, with less than a third of the 727 aquatic bird species adopting this method of food seeking.
Joshua Tyler and Dr. Jane Younger researched the development of diving in modern waterbirds to see how diving affected the birds' physical traits (morphology), how the species developed to enhance variety (rate of speciation), and how vulnerable the species were to extinction.
The study, published in the Proceedings of the Royal Society B, discovered that diving evolved 14 times independently and that once a group gained the capacity to dive, subsequent evolution did not reverse this attribute.
The researchers discovered that the body size of diving birds developed differently depending on the sort of diving they undertook.
Wing divers, such as penguins and puffins, utilize their wings to propel themselves through the water.
These birds have greater body proportions that are specialized for swimming.
Birds that "foot dive," such as cormorants, kick their feet to swim and are similarly bigger in body size than the wing divers.
Plunge divers, such as gulls and gannets, on the other hand, plunge vertically from the air to seize their food.
The researchers observed these species tended to be more limited in their body size since they were better adapted for flying than swimming.
While there was no significant difference in speciation rates between diving birds and non-diving species, the researchers discovered that several diving birds looked to be more prone to extinction than non-diving species.
The methodologies developed by the researchers might be used to assist conservationists to anticipate which species are most at risk of extinction from an evolutionary standpoint.
Josh Tyler, a first author of the research and Ph.D. student at the Milner Centre for Evolution at the University of Bath, said: "Our work reveals that rather than being a random process, there are predictable patterns to evolution", as per ScienceDaily.
Divers, for example, have increased blood volume and store more oxygen in the form of oxyhemoglobin in blood and oxymyoglobin in muscle than non-divers, as per Bird Watching.
For example, Tufted Ducks have 70% more oxygen per kilogram of body weight than Mallards.
Carbon dioxide accumulation encourages birds to breathe and can eventually compel breathing, resulting in death for a diver.
Divers have a greater buffering mechanism, which allows them to store more carbon dioxide before breathing.
A reflex causes the overall metabolism to drop about six seconds into a dive.
The heart rate decreases by roughly 50%, and blood is redirected from bodily regions that can handle low oxygen levels, such as the skin, viscera, and muscle, to the heart and brain, which require a steady supply.
The activities assist to save a limited amount of oxygen.
Rapid muscle activity can be performed anaerobically if necessary. Lactic acid will be eliminated biologically after oxygen is reintroduced.
Plunge divers, which include terns, kingfishers, and gannets, see fish from the air and plunge headfirst into the water, often from enormous distances.
The birds seize the fish in their beak if the plunges are successful.
If they miss, they swim to the surface and swallow nothing except their pride.
Pursuit divers hunt fish underwater.
Because their hips are small and their body is cylindrical, they travel effectively through the water.
Their legs are situated far back on their body, where they operate as propellers and rudders.
Loons and penguins are excellent examples of pursuit divers.
Another issue with diving and underwater swimming are that natural selection favored light weight and buoyancy throughout the early development of birds.
Such features are desirable for most lifestyles but expensive to divers, which want to dedicate their energy to hunting prey, not to counteracting buoyancy.
As a result, they wish to be bulky.
Divers are heavier than non-divers because their long bones are loaded with marrow, their muscle mass is larger (particularly in the legs), and most have heavier plumages, which they make waterproof with oil from their bigger uropygial, or preen, gland.
