Marine mortality in the river? Atlantic salmon smolts under high predation pressure in the last kilometres of a river monitored for stock assessment

2019 ◽  
Vol 27 (1) ◽  
pp. 92-101 ◽  
Author(s):  
Hugo Flávio ◽  
Richard Kennedy ◽  
Dennis Ensing ◽  
Niels Jepsen ◽  
Kim Aarestrup
Keyword(s):  
Atlantic Salmon ◽  
Stock Assessment ◽  
Predation Pressure ◽  
High Predation ◽  
High Predation Pressure

scholarly journals Trophic shift and the origin of birds

2020 ◽  
Author(s):  
Yonghua Wu
Keyword(s):  
Predation Risk ◽  
Digestive System ◽  
Predation Pressure ◽  
Flapping Flight ◽  
Foraging Efficiency ◽  
Fat Digestion ◽  
Trophic Shift ◽  
High Predation ◽  
High Predation Pressure ◽  
Selection Of

AbstractBirds are characterized by evolutionary specializations of both locomotion (e.g., flapping flight) and digestive system (toothless, crop, and gizzard), while the potential selection pressures responsible for these evolutionary specializations remain unclear. Here we used a recently developed molecular phyloecological method to reconstruct the diets of the ancestral archosaur and of the common ancestor of living birds (CALB). Our results showed that the ancestral archosaur exhibited a predominant Darwinian selection of protein and fat digestion and absorption, whereas the CALB showed a marked enhanced selection of carbohydrate and fat digestion and absorption, suggesting a trophic shift from carnivory to herbivory (fruit, seed, and/or nut-eater) at the archosaur-to-bird transition. The evolutionary shift of the CALB to herbivory may have essentially made them become a low-level consumer and, consequently, subject to relatively high predation risk from potential predators such as gliding maniraptorans, from which birds descended. Under the relatively high predation pressure, ancestral birds with gliding capability may have then evolved not only flapping flight as a possible anti-predator strategy against gliding predatory maniraptorans but also the specialized digestive system as an evolutionary tradeoff of maximizing foraging efficiency and minimizing predation risk. Our results suggest that the powered flight and specialized digestive system of birds may have evolved as a result of their tropic shift-associated predation pressure.

Ant assemblage composition explains high predation pressure on artificial caterpillars during early night

2019 ◽  
Vol 45 (3) ◽  
pp. 547-554 ◽  
Author(s):  
Xiang Liu ◽  
Zhenghong Wang ◽  
Chenyu Huang ◽  
Manru Li ◽  
Farkhanda Bibi ◽  
...  
Keyword(s):  
Predation Pressure ◽  
Assemblage Composition ◽  
High Predation ◽  
High Predation Pressure

scholarly journals Ctenophore population recruits entirely through larval reproduction in the central Baltic Sea

2012 ◽  
Vol 8 (5) ◽  
pp. 809-812 ◽  
Author(s):  
Cornelia Jaspers ◽  
Matilda Haraldsson ◽  
Sören Bolte ◽  
Thorsten B. H. Reusch ◽  
Uffe H. Thygesen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Egg Production ◽  
Mortality Rates ◽  
Predation Pressure ◽  
Arctic Regions ◽  
Comb Jelly ◽  
High Predation ◽  
High Predation Pressure

The comb jelly Mertensia ovum, widely distributed in Arctic regions, has recently been discovered in the northern Baltic Sea. We show that M. ovum also exists in the central Baltic but that the population consists solely of small-sized larvae (less than 1.6 mm). Despite the absence of adults, eggs were abundant. Experiments revealed that the larvae were reproductively active. Egg production and anticipated mortality rates suggest a self-sustaining population. This is the first account of a ctenophore population entirely recruiting through larval reproduction (paedogenesis). We hypothesize that early reproduction is favoured over growth to compensate for high predation pressure.

Weed seed predation rate in cereals as a function of seed density and patch size, under high predation pressure by rodents

Weed Research ◽  
2013 ◽  
Vol 54 (2) ◽  
pp. 186-195 ◽  
Author(s):  
D Daedlow ◽  
P R Westerman ◽  
B Baraibar ◽  
S Rouphael ◽  
B Gerowitt
Keyword(s):  
Seed Predation ◽  
Patch Size ◽  
Predation Rate ◽  
Predation Pressure ◽  
Seed Density ◽  
Weed Seed ◽  
High Predation ◽  
High Predation Pressure

scholarly journals Molecular phyloecology suggests a trophic shift concurrent with the evolution of the first birds

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yonghua Wu
Keyword(s):  
Predation Risk ◽  
Digestive System ◽  
Common Ancestor ◽  
Predation Pressure ◽  
Flapping Flight ◽  
Foraging Efficiency ◽  
Trophic Shift ◽  
High Predation ◽  
The Common ◽  
High Predation Pressure

AbstractBirds are characterized by evolutionary specializations of both locomotion (e.g., flapping flight) and digestive system (toothless, crop, and gizzard), while the potential selection pressures responsible for these evolutionary specializations remain unclear. Here we used a recently developed molecular phyloecological method to reconstruct the diets of the ancestral archosaur and of the common ancestor of living birds (CALB). Our results suggest a trophic shift from carnivory to herbivory (fruit, seed, and/or nut eater) at the archosaur-to-bird transition. The evolutionary shift of the CALB to herbivory may have essentially made them become a low-level consumer and, consequently, subject to relatively high predation risk from potential predators such as gliding non-avian maniraptorans, from which birds descended. Under the relatively high predation pressure, ancestral birds with gliding capability may have then evolved not only flapping flight as a possible anti-predator strategy against gliding predatory non-avian maniraptorans but also the specialized digestive system as an evolutionary tradeoff of maximizing foraging efficiency and minimizing predation risk. Our results suggest that the powered flight and specialized digestive system of birds may have evolved as a result of their tropic shift-associated predation pressure.

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