Maternal experience brings an evolutionary advantage

Date:September 22, 2015

Source:Universität Basel

Summary:Using a species of butterfly as an example, researchers have demonstrated how insects adapt their offspring to changing environmental conditions. The paper shows that females pass on their own experience to their brood, even if this experience was not necessarily ideal. This rapid adaptation has huge implications for our understanding of speciation in insects.

In their study, the researchers working under Prof. Andreas Erhardt firstly confirmed their earlier results, which showed that parent generations of butterflies can condition their offspring to the quality of forage plants that they experienced as larvae. Secondly, they were able to provide evidence for the first time that the mothers of these offspring change their egg-laying behavior and prefer to deposit their eggs on plants on which they themselves once developed.

The Basel-based environmental scientists showed that young females of the small cabbage white (Pieris rapae) were more precise than their parents in laying their eggs on the very same plants that they (and their parents) experienced as larvae. This provided the scientists with proof of the adaptation process. In their study, the scientists used cabbage as a host plant and added either a large or a small quantity of nitrogen to it, bearing in mind that fertilization with nitrogen is favorable for the development of butterfly larvae. Although the plant containing more nitrogen therefore represented the better choice, females that had developed as caterpillars on plants with less nitrogen showed a tendency to lay their eggs on the unfertilized cabbage.

Accelerated speciation

This kind of breeding behavior has implications for our understanding of evolutionary and ecological processes. The conditioning of the offspring to the parents’ own experiences only takes place if the offspring grow up in a similar environment to the parent generation. In species in which this conditioning occurs, the preference for the corresponding experience is therefore reinforced with each generation. This breeds offspring that are increasingly better adapted to the respective host plant, even if this actually doesn’t provide optimal conditions — and, as a result, new species can emerge more quickly and more easily.

Although the conditioning may have succeeded in reducing the disadvantage caused by the less-favorable environment, it has not eradicated it completely. In compensation, females that accept or even prefer the disadvantageous environmental conditions have access to a greater selection of plants on which to lay their eggs, which leads to a reduction in competition within the species.


Story Source:

The above post is reprinted from materials provided by Universität Basel. Note: Materials may be edited for content and length.


Journal Reference:

  1. Fabian Cahenzli, Barbara A. Wenk, Andreas Erhardt. Female butterflies adapt and allocate their progeny to the host-plant quality of their own larval experience. Ecology, 2015; 96 (7): 1966 DOI: 10.1890/14-1275.1

Will you have male or female offspring?

Date:September 22, 2015

Source:Swiss National Science Foundation (SNSF)

Summary:According to a well-known theory in evolutionary biology healthy females should give birth to more males than females. A study shows why this is not always true.

According to popular belief, whether you have a baby girl or boy is purely a matter of chance. And yet, a study published several years ago shows that mothers in stressful jobs, for instance, give birth to more girls than boys. The correlation between such shifts in the offspring sex ratio and the mother’s overall state is something that evolutionary biologists are familiar with from other animal species. One influential hypothesis puts natural selection as an explanation for the imbalances observed.

Strong males with high reproductive success

The Trivers-Willard hypothesis states that it is beneficial for mothers to be able to adjust the sex of their offspring in response to their own state of health. Accordingly, a female in good condition should give birth to more male offspring. This is because successful males have the potential to produce more children in their lifetime than successful females. By producing strong sons, healthy mothers increase the probability of their own genes being widely distributed. Conversely, low-ranking females who are not in such good shape are more likely to produce daughters, because the chances of giving birth to a future dominant male are poor.

“However, it’s not quite as simple as that,” points out biologist Peter Neuhaus sponsored by the Swiss National Science Foundation, based at the University of Calgary in Canada. Taking the example of a model with data from Columbian ground squirrels and Canadian bighorn sheep, Neuhaus — together with colleagues from the UK, the US, France and South Africa — has demonstrated in an article published in Nature magazine that optimal reproduction also depends on a series of other factors.

Dead before reaching sexual maturity

Bighorn ewes, for instance, give birth to only one lamb a year. Most females mate with the dominant ram, which means many of the other males don’t get a chance. Females in a good state often pass on their condition and so can be expected to “to make supermales,” as Neuhaus explains. Nonetheless, the healthy females do not produce more male than female offspring. As the model demonstrates, other parameters, such as the fact that a large number of males die before reaching sexual maturity, play a central role in assessing reproductive potential.

But what have sheep got to do with mothers in jobs with some degree of stress? Nobody doubts that they have more girls, but Neuhaus advises caution: “Evolution is very complex. To understand how it works, you need to take into account as many factors as possible that could influence reproductive potential.”


Story Source:

The above post is reprinted from materials provided by Swiss National Science Foundation (SNSF). Note: Materials may be edited for content and length.


Journal Reference:

  1. Susanne Schindler, Jean‐Michel Gaillard, André Grüning, Peter Neuhaus, Lochran W. Traill, Shripad Tuljapurkar, Tim Coulson. Sex‐specific demography and generalization of the Trivers–Willard theory. Nature, 2015; DOI: 10.1038/nature14968

Could being a good father send you to an early grave?

Males with low quality partners put more effort into parental duties to compensate for the shortcomings of their mate, and pay the price by dying younger

Date:
September 22, 2015
Source:
eLife
Summary:
Non-genetic inheritance plays a huge role in determining the characteristics of offspring. For example, bad parenting creates bad parents-to-be, while well-cared for larvae mature into high quality parents.

When a good insect father pairs with a bad mother, he risks being exploited by her for childcare and could bear the ultimate cost by dying young.

A new study carried out with burying beetles also shows that bad parenting creates bad parents-to-be, while well-cared for larvae mature into high quality parents.

The research will be published in the journal eLife.

“Parents obviously play a huge role in determining the characteristics of their offspring,” says lead researcher Professor Rebecca Kilner from the Department of Zoology at the University of Cambridge.

“The aim of our study was to investigate non-genetic ways that parents achieve this.”

This is important because non-genetic inheritance could speed up the rate at which animal behaviour evolves and adapts in a rapidly changing world.

Whether examining mothers or fathers, the research team found that individuals that received no care as larvae were less effective at raising a large brood as parents, and died younger. In contrast, high quality care not only produces a larger brood, but individual offspring with a higher mass. This is consistent with previous studies.

“We found that parental care provides a mechanism for non-genetic inheritance. Good quality parents produce offspring that become good parents themselves, while offspring that receive poor parenting then become low quality parents. Our experiments show how parental care allows offspring to inherit characteristics of their parents, but non-genetically,” she says.

However, the team also found that offspring pay a cost for receiving high quality care, because it makes them vulnerable to exploitation if they pair up with a lower quality partner. This may explain why animals often choose a mate who is willing to put in a similar amount of effort as they as a parent. In this way, they are less vulnerable to exploitation.

The burying beetle, Nicrophorus vespilloides, uses the carcass of a small vertebrate such as a mouse as an edible nest for its young. As its name suggests, a breeding pair buries the carcass and preserves it with an antibacterial secretion. The mother lays eggs nearby in the soil, and the larvae crawl to the carcass when they hatch. Although the larvae can feed themselves, they also beg both parents for partly-digested food from the carcass.

In the current study, when males were paired with females that had received no post-hatching care as larvae, they had significantly shorter lives than those whose partners had received more care. The most likely explanation is that males with low quality partners put more effort into parental duties to compensate for the shortcomings of their mate, and paid the price by dying younger.


Story Source:

The above post is reprinted from materials provided by eLife. Note: Materials may be edited for content and length.


Journal Reference:

  1. RM Kilner, G Boncoraglio, JM Henshaw, BJM Jarrett, O De Gasperin, A Attisano, H Kokko. Parental effects alter the adaptive value of an adult behavioural trait. eLife, 2015; 4 DOI: 10.7554/eLife.07340

How your brain decides blame and punishment, and how it can be changed

Date:September 16, 2015

Source:Vanderbilt University

Summary:Juries in criminal cases typically decide if someone is guilty, then a judge determines a suitable level of punishment. New research confirms that these two separate assessments of guilt and punishment — though related — are calculated in different parts of the brain. In fact, researchers have found that they can disrupt and change one decision without affecting the other.

New work by researchers at Vanderbilt University and Harvard University confirms that a specific area of the brain, the dorsolateral prefrontal cortex, is crucial to punishment decisions. Researchers predicted and found that by altering brain activity in this brain area, they could change how subjects punished hypothetical defendants without changing the amount of blame placed on the defendants.

“We were able to significantly change the chain of decision-making and reduce punishment for crimes without affecting blameworthiness,” said René Marois, professor and chair of psychology at Vanderbilt and co-principal author of the study. “This strengthens evidence that the dorsolateral prefrontal cortex integrates information from other parts of the brain to determine punishment and shows a clear neural dissociation between punishment decisions and moral responsibility judgements.”

The research titled “From Blame to Punishment: Disrupting Prefrontal Cortex Activity Reveals Norm Enforcement Mechanisms” was published on Sept. 17 in the journal Neuron.

The Experiment

The researchers used repetitive transcranial magnetic stimulation (rTMS) on a specific area of the dorsolateral prefrontal cortex to briefly alter activity in this brain region and consequently change the amount of punishment a person doled out.

“Many studies show the integrative function of the dorsolateral prefrontal cortex in relatively simple cognitive tasks, and we believe that this relatively basic process forms the foundation for far more complex forms of behavior and decision-making, such as norm enforcement,” said lead author Joshua Buckholtz, now an assistant professor of psychology at Harvard.

The researchers conducted experiments with 66 volunteer men and women. Participants were asked to make punishment and blameworthiness decisions in a series of scenarios in which a suspect committed a crime. The scenarios varied by harm caused (ranging from property loss to grievous injury and death) and how culpable the suspect was for the act (fully responsible or not, due to mitigating circumstances.) Half of the subjects received active rTMS while the other half of the subjects received a sham or placebo version of rTMS.

Level of Harm

Across all participants and all trials, both culpability and level of harm were significant predictors of the amount of punishment the subjects deemed appropriate. But subjects receiving active rTMS chose significantly lower punishments for fully culpable suspects than did those subjects receiving sham rTMS, particularly in scenarios that resulted in low to moderate harm. Additional analyses suggested that the effect was due to impaired integration of signals for harm and culpability.

“Temporarily disrupting the dorsolateral prefrontal cortex function appears to alter how people use information about harm and culpability to render these decisions. In other words punishment requires that people balance these two influences, and the rTMS manipulation interfered with this balance, especially under conditions in which these factors are dissonant, such as when the intent is clear but the harm outcome is mild,” said Buckholtz.

Implications

The research team’s main goal in this work is to expand the knowledge of how the brain assesses and then integrates information relevant to guilt and punishment decisions. It will also advance the burgeoning interdisciplinary study of law and neuroscience.

“This research gives us deeper insights into how people make decisions relevant to law, and particularly how different parts of the brain contribute to decisions about crime and punishment. We hope that these insights will help to build a foundation for better understanding, and perhaps one day better combatting, decision-making biases in the legal system,” said co-author Owen Jones, professor of law and biological sciences at Vanderbilt and director of the MacArthur Foundation Research Network on Law and Neuroscience.


Story Source:

The above post is reprinted from materials provided by Vanderbilt University. The original item was written by Amy Wolf. Note: Materials may be edited for content and length.


Journal Reference:

  1. Joshua W. Buckholtz, Justin W. Martin, Michael T. Treadway, Katherine Jan, David H. Zald, Owen Jones, René Marois. From Blame to Punishment: Disrupting Prefrontal Cortex Activity Reveals Norm Enforcement Mechanisms. Neuron, 2015; DOI: 10.1016/j.neuron.2015.08.023

How childhood stress can affect female fertility

Date:September 10, 2015

Source:Taylor & Francis

Summary:Can events you endured as a child really impact your ability to have children yourself? New research examines the mechanism by which adverse experiences in childhood impact female fertility. Researchers explore the hypothesis that negative experiences in childhood can result in menstrual cycle irregularities, which consequently impact fertility. They relate their hypothesis to life-history theory, which talks of balancing the preservation of one’s health and the production of offspring that will survive to reproduce themselves.

Can events you endured as a child really impact your ability to have children yourself? New research in the Journal of Psychosomatic Obstetrics & Gynecology examines the mechanism by which adverse experiences in childhood impact female fertility. In their paper ‘Adverse childhood event experiences, fertility difficulties and menstrual cycle characteristics’, Marni B. Jacobs et al. explore the hypothesis that negative experiences in childhood can result in menstrual cycle irregularities, which consequently impact fertility. They relate their hypothesis to life-history theory, which talks of balancing the preservation of one’s health and the production of offspring that will survive to reproduce themselves, and theorize that “early life stressors may predispose an individual to adaptively suppress fertility when situations are less than optimal, leading to periods of fertility difficulties even following previous births.”

The study examined data from 774 women of reproductive age, 195 of whom were pregnant. It analysed fertility difficulties, menstrual cycle irregularities and adverse childhood experiences, through a mixture of in-person interviews and take-home questionnaires.

Following their research, the team came to the conclusion that those women who had experienced negative events at a young age — such as “abuse, neglect, household dysfunction or parental substance abuse” — were more likely to have faced fertility difficulties and abnormal absences of menstruation lasting three months or more, and also took a longer time to get pregnant. Their research also suggests that certain harmful events in childhood can potentially have a greater impact on fertility than others.


Story Source:

The above post is reprinted from materials provided by Taylor & Francis. Note: Materials may be edited for content and length.


Journal Reference:

  1. Marni B. Jacobs, Renee D. Boynton-Jarrett, Emily W. Harville. Adverse childhood event experiences, fertility difficulties and menstrual cycle characteristics. Journal of Psychosomatic Obstetrics & Gynecology, 2015; 36 (2): 46 DOI: 10.3109/0167482X.2015.1026892

Children’s Complex Thinking Skills Begin Before Going to School

Jan. 23, 2013 — New research at the University of Chicago and the University of North Carolina at Chapel Hill shows that children begin to show signs of higher-level thinking skills as young as age 4 ½. Researchers have previously attributed higher-order thinking development to knowledge acquisition and better schooling, but the new longitudinal study shows that other skills, not always connected with knowledge, play a role in the ability of children to reason analytically.


The findings, reported in January in the journal Psychological Science, show for the first time that children’s executive function has a role in the development of complicated analytical thinking. Executive function includes such complex skills as planning, monitoring, task switching, and controlling attention. High, early executive function skills at school entry are related to higher than average reasoning skills in adolescence.

Growing research suggests that executive function may be trainable through pathways, including preschool curriculum, exercise and impulse control training. Parents and teachers may be able to help encourage development of executive function by having youngsters help plan activities, learn to stop, think, and then take action, or engage in pretend play, said lead author of the study, Lindsey Richland, assistant professor in comparative human development at the University of Chicago.

Although important to a child’s education, “little is known about the cognitive mechanisms underlying children’s development of the capacity to engage in complex forms of reasoning,” Richland said.

The new research is reported in the paper “Early Executive Function Predicts Reasoning Development” and follows the development of complex reasoning in children from before the time they go to school until they are 15. Richland’s co-author is Margaret Burchinal, senior scientist at the Frank Porter Graham Child Development Institute at the University of North Carolina at Chapel Hill.

The two studied the acquisition of analogical thinking, one form of complex reasoning. “The ability to see relationships and similarities between disparate phenomena is fundamental to analytical and inductive reasoning, and is closely related to measurements of general fluid intelligence,” said Richland. Developing complex reasoning ability is particularly fundamental to the innovation and adaptive thinking skills necessary for a modern workforce, she pointed out.

Richland and Burchinal studied a database of 1,364 children who were part of the Early Child Care and Youth Development study from birth through age 15. The group was fairly evenly divided between boys and girls and included families from a diverse cross-section of ethnic and income backgrounds.

The current study examined tests children took when they were 4 ½, when they were in first grade, third grade, and when they were 15. Because the study was longitudinal, the same children were tested at each interval. Among the tests they took were ones to measure analytical reasoning, executive function, vocabulary knowledge, short-term memory and sustained attention.

Children were tested at 4 ½ on their ability to monitor and control their automatic responses to stimuli. In first grade they worked on a test that judged their ability to move objects in a “Tower of Hanoi” game, in which they had to move disks between pegs in a specific order.

In third grade and at 15 year olds, they were tested on their ability to understand analogies, asked in third grade for instance to complete the question “dog is to puppy as cat is to__?” At 15 year olds, they were asked to complete written tests of analogies.

The study found a strong relationship between high scores among children who, as preschoolers, had strong vocabularies and were good at monitoring and controlling their responses to later ability on tests of understanding analogies.

“Overall, these results show that knowledge is necessary for using thinking skills, as shown by the importance of early vocabulary, but also inhibitory control and executive function skills are important contributors to children’s analytical reasoning development,” Richland said.

The National Academy of Education/Spencer Foundation, the Office of Naval Research and the National Science Foundation supported the research.

 

Story Source:

The above story is reprinted from materials provided byUniversity of Chicago.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. L. E. Richland, M. R. Burchinal. Early Executive Function Predicts Reasoning DevelopmentPsychological Science, 2012; 24 (1): 87 DOI:10.1177/0956797612450883
University of Chicago (2013, January 23). Children’s complex thinking skills begin before going to school. ScienceDaily. Retrieved January 28, 2013, from http://www.sciencedaily.com/releases/2013/01/130123164858.htm