Harry H. Marshall

With biodiversity loss escalating globally, a step change is needed in our capacity to accurately monitor species populations across ecosystems. Robotic and autonomous systems (RAS) offer technological solutions that may substantially advance terrestrial biodiversity monitoring, but this potential is yet to be considered systematically. We used a modified Delphi technique to synthesize knowledge from 98 biodiversity experts and 31 RAS experts, who identified the major methodological barriers that currently hinder monitoring, and explored the opportunities and challenges that RAS offer in overcoming these barriers. Biodiversity experts identified four barrier categories: site access, species and individual identification, data handling and storage, and power and network availability. Robotics experts highlighted technologies that could overcome these barriers and identified the developments needed to facilitate RAS-based autonomous biodiversity monitoring. Some existing RAS could be optimized relatively easily to survey species but would require development to be suitable for monitoring of more ‘difficult’ taxa and robust enough to work under uncontrolled conditions within ecosystems. Other nascent technologies (for instance, new sensors and biodegradable robots) need accelerated research. Overall, it was felt that RAS could lead to major progress in monitoring of terrestrial biodiversity by supplementing rather than supplanting existing methods. Transdisciplinarity needs to be fostered between biodiversity and RAS experts so that future ideas and technologies can be codeveloped effectively.

Recognition plays a key role in the social lives of gregarious species, enabling animals to distinguish among social partners and tailor their behaviour accordingly. As domesticated animals regularly interact with humans, as well as members of their own species, we might expect mechanisms used to discriminate between conspecifics to also apply to humans. Given that goats can combine visual and vocal cues to recognize one another, we investigated whether this cross-modal recognition extends to discriminating among familiar humans. We presented 28 goats with facial photographs of familiar people and two repeated playbacks of a voice, either congruent (from the same person) or incongruent with that photograph (from a different person). When cues were incongruent, violating their expectations, we expected goats to respond faster and for longer after playbacks and show increases in physiological arousal (increased heart rate and/or decreased heart rate variability). We found the increase in latency that goats took to respond as the playback series progressed was greater when the face and voice were incongruent. As differences were not as predicted and only observed in one response measured, our evidence is tentative, but the variation in latency to look between congruency conditions suggests goat cross-modal recognition extends to humans. If this is the case, not only would this further demonstrate the flexibility of complex recognition systems to discriminate among members of a very different species, but indicates goats can produce mental representations for familiar people, a key component of individual recognition.

Research in medicine and evolutionary biology suggests that the sequencing of parental investment has a crucial impact on offspring life history and health. Here, we take advantage of the synchronous birth system of wild banded mongooses to test experimentally the lifetime consequences to offspring of receiving extra investment prenatally versus postnatally. We provided extra food to half of the breeding females in each group during pregnancy, leaving the other half as matched controls. This manipulation resulted in two categories of experimental offspring in synchronously born litters: (i) ‘prenatal boost’ offspring whose mothers had been fed during pregnancy, and (ii) ‘postnatal boost’ offspring whose mothers were not fed during pregnancy but who received extra alloparental care in the postnatal period. Prenatal boost offspring lived substantially longer as adults, but postnatal boost offspring had higher lifetime reproductive success (LRS) and higher glucocorticoid levels across the lifespan. Both types of experimental offspring had higher LRS than offspring from unmanipulated litters. We found no difference between the two experimental categories of offspring in adult weight, age at first reproduction, oxidative stress or telomere lengths. These findings are rare experimental evidence that prenatal and postnatal investments have distinct effects in moulding individual life history and fitness in wild mammals. This article is part of the theme issue ‘Evolutionary ecology of inequality’.

Reading another animal’s emotional state can enable receivers to anticipate their behavioural motivations, which is important in guiding interactions with that individual. For species living closely alongside humans, the emotional cues that people express can be almost as informative as those of conspecifics. Goats can discriminate differences in emotional valence present in another goat’s calls, and we investigated whether this ability extends to human speech. We presented goats with a habituation-dishabituation-rehabituation paradigm, where they experienced multiple playbacks of a familiar or unfamiliar human voice conveying a single emotional valence (e.g., angry; habituation phase), before the valence of the voice changed (e.g., happy; dishabituation phase) and then reversed again in-line with the habituation phase (e.g., angry; rehabituation phase). Over the habituation phase, goat behavioural responses decreased, showing evidence of having habituated to the playback stimuli presented. Following a change in emotional valence (dishabituation phase), although goats were overall less likely to respond, those that did looked for longer, suggesting they had perceived the shift in emotional content conveyed in human voice playbacks. We found no changes in physiological arousal (heart rate or heart rate variability) with shifts in playback valence. Goats, as a domesticated species, may have developed a sensitivity to our cues over their long association with humans, but the differences in individual behaviour towards the playback paradigm could highlight a role for learning and individual experience in particular on interspecific emotional communication.

The cost of reproduction plays a central role in evolutionary theory, but the identity of the underlying mechanisms remains a puzzle. Oxidative stress has been hypothesized to be a proximate mechanism that may explain the cost of reproduction. We examine three pathways by which oxidative stress could shape reproduction. The “oxidative cost” hypothesis proposes that reproductive effort generates oxidative stress, while the “oxidative constraint” and “oxidative shielding” hypotheses suggest that mothers mitigate such costs through reducing reproductive effort or by pre‐emptively decreasing damage levels, respectively. We tested these three mechanisms using data from a long‐term food provisioning experiment on wild female banded mongooses (Mungos mungo). Our results show that maternal supplementation did not influence oxidative stress levels, or the production and survival of offspring. However, we found that two of the oxidative mechanisms co‐occur during reproduction. There was evidence of an oxidative challenge associated with reproduction that mothers attempted to mitigate by reducing damage levels during breeding. This mitigation is likely to be of crucial importance, as long‐term offspring survival was impacted by maternal oxidative stress. This study demonstrates the value of longitudinal studies of wild animals in order to highlight the interconnected oxidative mechanisms that shape the cost of reproduction.

Mechanistic models suggest that individuals’ memories could shape home range patterns and dynamics, and how neighbors share space. In social species, such dynamics of home range overlap may be affected by the pre-dispersal memories of immigrants. We tested this “immigrant knowledge hypothesis” in a wild population of chacma baboons (Papio ursinus). We predicted that overlap dynamics with a given neighboring troop’s home range should reflect males’ adaptive interests in overlap when the alpha male had immigrated from this neighboring troop but less so when the alpha male originated from elsewhere. We used data collected between 2005 and 2013 on two neighboring troops in Namibia, comprising GPS records of daily ranges, male natal origins, daily females’ reproductive status, and a satellite index of vegetation growth. We found support for our prediction in line with male reproductive strategies but not in line with foraging conditions. In periods with a higher relative number of fertile females over adult males in the focal troop, male baboons would benefit from reducing overlap with their neighbors to mitigate the costs of between-troop mating competition. This was indeed observed but only when the alpha male of the focal troop was an immigrant from that neighboring troop, and not with alpha males of other origins, presumably due to their different knowledge of the neighboring troop. Our findings highlight the role of reproductive competition in the range dynamics of social groups, and suggest that spatial segregation between groups could increase through the combination of dispersal and memory.