Future challenges in cephalopod research

We thank Anto´nio M. de Frias Martins, past President of the Unitas Malacologica and Peter Marko, President of the American Malacological Society for organizing the 2013 World Congress of Malacology, and the Cephalopod International Advisory Committee for endorsing a symposium held in honour of Malcolm R. Clarke. In particular, we would like to thank the many professional staff from the University of the Azores for their hospitality, organization, troubleshooting and warm welcome to the Azores. We also thank Malcolm Clarke’s widow, Dorothy, his daughter Zoe¨, Jose´ N. Gomes-Pereira and numerous colleagues and friends of Malcolm’s from around the world for joining us at Ponta Delgada. We are grateful to Lyndsey Claro (Princeton University Press) for granting copyright permissions.Peer reviewedPublisher PD

Leaving a solitary life behind: Evolutionary processes leading to sociality in animals

Die Entwicklung stabiler Tiergruppen ist ein wichtiger Übergang in der Evolution, der aufgrund des selektiven Drucks, der mit sozialen Interaktionen verbunden ist, Veränderungen in der Populationsstruktur und in den aufkommenden Eigenschaften mit sich bringt. Die Sozialität basiert auf Kooperation, ein evolutionäres Puzzle in der darwinistischen Theorie, das auf der Konkurrenz um begrenzte Ressourcen beruht. Im ersten Kapitel stellen wir die Bedeutung der Verwandtschaftsselektion (i.e. Nepotismus) in Frage, um das Auftreten von Tiergruppen zu erklären, das das aktuelle Paradigma darstellt. Diese Theorie legt nahe, dass genetische Ähnlichkeit notwendig ist, um die Konkurrenz zwischen Individuen zu reduzieren, die eine Kooperation ermöglichen. Wir schlagen einen alternativen Rahmen vor, der die zahlreichen und unterschiedlichen Arten berücksichtigt, in denen die elterliche Fürsorge die Entwicklung des Gruppenlebens katalysiert haben könnte. Wir betonen die Bedeutung koevolutiver Prozesse zwischen Parasiten und Raubtieren mit elterlichen Investitionsstrategien, lange bevor ein Übergang zur Sozialität stattfinden kann. Aufbauend auf empirischen und theoretischen Erkenntnissen aus einem breiten Spektrum von Taxa, einschließlich Wirbeltieren und wirbellosen Tieren, schlagen wir vor, dass direkte Fitnessvorteile, die sich aus dem selektiven Druck ergeben, der mit der Evolution der elterlichen Fürsorge verbunden ist, die Kraft hinter dem Auftreten von Tiergruppen sind. In diesem Rahmen ist die Verwandtenselektion eher ein Verstärker oder sogar ein Nebenprodukt aus evolutionären Prozessen, die mit der elterlichen Fürsorge in Verbindung stehen, und nicht die Hauptvoraussetzung für die Entwicklung der Zusammenarbeit. Im zweiten Kapitel konzentrieren wir uns auf die Untersuchung fakultativ sozialer Spezies, um die Prozesse zu verstehen, die eine einsame Spezies zu einem Gruppenleben führen. In diesem Sinne beschreiben wir das Sozialsystem eines fakultativ sozialen Primaten mit gemeinschaftlicher Zucht, Microcebus murinus, anhand von Daten über mehr als 200 Individuen aus einer Wildpopulation. Durch die Untersuchung der gemeinsamen Schlafplatznutzung bei dieser einsamen Futtersuche wollen wir die soziale Flexibilität sowohl auf der Ebene der Art als auch auf der Ebene des Individuums charakterisieren. Wir finden Belege für die soziale Flexibilität bei philopatrischen Weibchen und zerstreuenden Männchen. Darüber hinaus zeigen wir, im Gegensatz zu früheren Ergebnissen, eine höhere Fähigkeit zur Sozialität und sozialen Flexibilität bei den Männchen. Unsere Ergebnisse deuten also darauf hin, dass die weibliche Gemeinschaftszucht möglicherweise nicht die einzige treibende Kraft für die Sozialität bei dieser Art ist, was den in Kapitel 1 dargelegten Rahmen kritisiert; und dass nicht verwandte Männchen genauso anfällig für die Bildung sozialer Gruppen sind wie verwandte Weibchen, was darauf hindeutet, dass die Verwandtschaftsauswahl auch nicht in der Lage ist, die Entwicklung der sozialen Systeme des Mausmakis zu erklären. Während wir in den ersten beiden Kapiteln die Übergänge zur Sozialität aus einer anpassungsorientierten Perspektive diskutiert haben, untersuchen wir in Kapitel 3.1 die Möglichkeit, dass die Sozialität bei Microcebus murinus ein passives Ergebnis der heterogenen Verteilung von Nahrungsressourcen und Schlafplätzen sein könnte. Wir finden keine Belege für einen Effekt der Verfügbarkeit von Nahrungsressourcen oder der Einschränkung der Nistplätze auf individuelle Sozialstrategien. Daher könnten die intrinsischen Vorteile, die mit dem gemeinsamen Schlafen und der gemeinsamen Nutzung eines Heimbereichs mit anderen verbunden sind, bei dieser Art im Spiel sein. In Kapitel 3.2 entwickeln wir die in Kapitel 3.1 angewandte Methode zur Beurteilung der Zuverlässigkeit der für jedes Individuum gesammelten Informationen, um mit Hilfe der Michaelis-Menten-Modellierung Heimatorte zu bauen. Wir glauben, dass dies ein potenziell nützliches Instrument für Studien in der freien Natur sein könnte, wo sowohl die Knappheit der Daten als auch die individuellen Unterschiede in der Menge der gesammelten Daten bewegungsökologische Analysen erschweren können. Abschließend betonen wir, dass die soziale Evolution ein vielfältiger Prozess ist, der mehrere Ebenen der Lebenskomplexität in sich birgt und miteinander verflochten ist und sich den Versuchen einer einheitlichen Erklärung ihrer Ursprünge widersetzt.The evolution of stable animal groups is a major transition in evolution entailing changes in population structure and emerging properties due to the selective pressures associated with social interactions. Sociality is based on cooperation, an evolutionary puzzle in Darwinian theory that is grounded on competition for limited resources. In the first chapter, we challenge the importance of kin selection (i.e. nepotism) to explain the appearance of animal groups, which is the current paradigm. This theory suggests that genetic similarity is needed to reduce competition between individuals allowing cooperation to be selected. We propose an alternative framework that takes into account the numerous and diverse ways in which parental care may have catalyzed the evolution of group living. We emphasize the importance of coevolutionary processes between parasites and predators with parental investment strategies long before transitions to sociality may occur. Building on empirical and theoretical evidence from a wide range of taxa, including vertebrates and invertebrates, we suggest that direct fitness benefits arising from selective pressures associated with parental care evolution are the force behind the appearance of animal groups. Under this framework, kin-selection is rather an enhancer or even a by-product derived from evolutionary processes related to parental care and not the main prerequisite for cooperation to evolve. In the second chapter, we focus on studying facultatively social species to understand the processes that lead a solitary species to become group-living. In this sense, we describe the social system of a facultatively social primate with communal breeding, Microcebus murinus, using data on more than 200 individuals from a wild population. By studying sleeping site sharing in this solitary foraging species, we aim to characterize the social flexibility both at the species as well as at the individual levels. We find evidence for social flexibility in philopatric females and dispersing males. Moreover, contrary to previous findings, we show a higher capacity for sociality and social flexibility in males. Thus, our results suggest that female communal breeding may not be the only force driving sociality in this species, criticizing the framework exposed in chapter 1; and that unrelated males may be as prone as related females to form social groups, which suggests that kin-selection is also unable to explain the evolution of mouse lemurs’ social systems. While in the first two chapters, we discussed transitions to sociality from an adaptationist perspective, in Chapter 3.1, we examine the possibility that sociality in Microcebus murinus may be a passive result of heterogeneous distribution of food resources and sleeping sites. We find no evidence for an effect of food resource availability or nesting limitation on individual social strategies. Thus, intrinsic benefits associated with sleeping together and sharing a home range with others may be at play in this species. In chapter 3.2, we develop the method used in chapter 3.1 to assess the reliability of information gathered per individual to construct home ranges using Michaelis-Menten modeling. We believe this might be a potentially useful tool for studies in the wild where scarcity of data as well as between-individual variation in the amount of data collected may hamper movement ecology analyses. We end by emphasizing that social evolution is a manifold process that embeds and intertwines several layers of life complexity, resisting attempts for unitary explanations of its origins

The role of visual adaptation in cichlid fish speciation

D. Shane Wright (1) , Ole Seehausen (2), Ton G.G. Groothuis (1), Martine E. Maan (1) (1) University of Groningen; GELIFES; EGDB(2) Department of Fish Ecology & Evolution, EAWAG Centre for Ecology, Evolution and Biogeochemistry, Kastanienbaum AND Institute of Ecology and Evolution, Aquatic Ecology, University of Bern.In less than 15,000 years, Lake Victoria cichlid fishes have radiated into as many as 500 different species. Ecological and sexual sel ection are thought to contribute to this ongoing speciation process, but genetic differentiation remains low. However, recent work in visual pigment genes, opsins, has shown more diversity. Unlike neighboring Lakes Malawi and Tanganyika, Lake Victoria is highly turbid, resulting in a long wavelength shift in the light spectrum with increasing depth, providing an environmental gradient for exploring divergent coevolution in sensory systems and colour signals via sensory drive. Pundamilia pundamila and Pundamilia nyererei are two sympatric species found at rocky islands across southern portions of Lake Victoria, differing in male colouration and the depth they reside. Previous work has shown species differentiation in colour discrimination, corresponding to divergent female preferences for conspecific male colouration. A mechanistic link between colour vision and preference would provide a rapid route to reproductive isolation between divergently adapting populations. This link is tested by experimental manip ulation of colour vision - raising both species and their hybrids under light conditions mimicking shallow and deep habitats. We quantify the expression of retinal opsins and test behaviours important for speciation: mate choice, habitat preference, and fo raging performance

Linking Dispersal to Local Population Dynamics: A Case Study Using a Headwater Salamander System

Dispersal can strongly influence local population dynamics and may be critical to species persistence in fragmented landscapes. Theory predicts that dispersal by resident stream organisms is necessary to offset the loss of individuals to downstream drift. However, there is a lack of empirical data linking dispersal and drift to local population dynamics in streams, leading to uncertainty regarding the general demographic significance of these processes and the power of drift to explain observed dispersal patterns. I assessed the contribution of dispersal along a first-order stream to population dynamics of the headwater salamander Gyrinophilus porphyriticus (Plethodontidae). I conducted mark–recapture surveys of two contiguous 500 m long sections of a study stream in June, July, and August of 1999, 2000, and 2001. Movement by G. porphyriticus larvae and adults showed a strong upstream bias in the study stream, as well as in 11 other streams that I surveyed. Using mark–recapture models and Akaike\u27s information criterion for model selection, monthly probability of dispersal from the downstream section to the upstream section of the study stream (mean ± 1 se) was estimated to be 0.02 ± 0.01. The probability of dispersal from the upstream section to the downstream section was 0.00 ± 0.00. Monthly survival probabilities did not differ between sections. Estimated monthly population growth rates were 1.01 ± 0.01 in both sections. Net dispersal from the downstream section to the upstream section contributed to the equality of population growth rates. Additionally, reproduction and individual condition were lower in the upstream section, suggesting that population stability and growth there (i.e., λ ≥ 1.0) may have been dependent on immigration from downstream. Similar interactions between dispersal and variation in local demographic rates along the stream continuum may underlie the distribution and abundance patterns of other organisms at multiple spatial scales. Greater empirical understanding of these interactions will improve conservation of stream biota. The strong upstream bias of G. porphyriticus movement suggests that dispersal is not a response to downstream drift. I propose an alternative model for the evolution of directionally biased dispersal based on the landscape-scale distribution of headwater habitats

Approaches for advancing scientific understanding of macrosystems

The emergence of macrosystems ecology (MSE), which focuses on regional- to continental-scale ecological patterns and processes, builds upon a history of long-term and broad-scale studies in ecology. Scientists face the difficulty of integrating the many elements that make up macrosystems, which consist of hierarchical processes at interacting spatial and temporal scales. Researchers must also identify the most relevant scales and variables to be considered, the required data resources, and the appropriate study design to provide the proper inferences. The large volumes of multi-thematic data often associated with macrosystem studies typically require validation, standardization, and assimilation. Finally, analytical approaches need to describe how cross-scale and hierarchical dynamics and interactions relate to macroscale phenomena. Here, we elaborate on some key methodological challenges of MSE research and discuss existing and novel approaches to meet them

Geometry shapes evolution of early multicellularity

Organisms have increased in complexity through a series of major evolutionary transitions, in which formerly autonomous entities become parts of a novel higher-level entity. One intriguing feature of the higher-level entity after some major transitions is a division of reproductive labor among its lower-level units. Although it can have clear benefits once established, it is unknown how such reproductive division of labor originates. We consider a recent evolution experiment on the yeast Saccharomyces cerevisiae as a unique platform to address the issue of reproductive differentiation during an evolutionary transition in individuality. In the experiment, independent yeast lineages evolved a multicellular "snowflake-like'' cluster form in response to gravity selection. Shortly after the evolution of clusters, the yeast evolved higher rates of cell death. While cell death enables clusters to split apart and form new groups, it also reduces their performance in the face of gravity selection. To understand the selective value of increased cell death, we create a mathematical model of the cellular arrangement within snowflake yeast clusters. The model reveals that the mechanism of cell death and the geometry of the snowflake interact in complex, evolutionarily important ways. We find that the organization of snowflake yeast imposes powerful limitations on the available space for new cell growth. By dying more frequently, cells in clusters avoid encountering space limitations, and, paradoxically, reach higher numbers. In addition, selection for particular group sizes can explain the increased rate of apoptosis both in terms of total cell number and total numbers of collectives. Thus, by considering the geometry of a primitive multicellular organism we can gain insight into the initial emergence of reproductive division of labor during an evolutionary transition in individuality.Comment: 7 figure

Neurochemical Levels Correlate with Population Level Differences in Social Structure and Individual Behavior in the Polyphenic Spider, \u3cem\u3eAnelosimus studiosus\u3c/em\u3e.

Anelosimus studiosus is a socially polyphenic spider. Individuals can be classified as social/tolerant or solitary/aggressive. These behavioral differences are associated with considerable variation in social structure. Here, we begin to examine the physiological differences that may underlie the behavioral dimorphism in this species and possible implications for the evolution of sociality. Octopamine is a neurotransmitter that has been found to elevate aggression in invertebrates. Serotonin has been shown, in some cases, to interact antagonistically with octopamine. We used High Pressure Liquid Chromatography with Electrochemical Detection to quantify levels of these neurochemicals among adult females from social (multi-female) and solitary (single-female) webs in east Tennessee. A subset of spiders was scored for individual social tendency. We found that higher octopamine levels are associated with a greater degree of aggression and intolerance, both at the individual level and the population level, while higher levels of serotonin are found in multi-female colonies and social individuals

Claims, Evidence and Reasoning: A Framework for Evidence-Based Writing on the subject of Evolution

The aim of this qualitative research was to explore how students presented reasoned arguments supported by evidence and reasoning after receiving constructivist-based instruction. The author documents the details of the results and uses related research literature to construct meaning and validate constructivist pedagogy and the evidencebased writing instruction. The progress of twenty students’ ability to write a claim, give specific evidence and reasoning was followed throughout the investigation. Three themes emerged from this investigation: students showed a steady trend of intellectual growth over time, students benefitted when they constructed their own learning, and students struggled with written reasoning and connecting reasoning to broader scientific concepts. Students showed overall growth with all students making gains throughout the investigation