Optimizing mating encounters by sexually dimorphic movements

Mizumoto, Nobuaki; Abe, Masato S.; Dobata, Shigeto

doi:10.1098/rsif.2017.0086

Cited by 22 publications

(26 citation statements)

References 38 publications

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“…When only one agent can drop a marker, our unique solution is asymmetric: one agent turns once while the other turns three times (see Theorem ). This observation goes in the same direction as in Mizumoto et al (). On the other hand, we also find symmetric solutions, for example the

({\overset{true‾}{f}}_{3}, {\overset{true‾}{g}}_{3})

solution found in Theorem for the two marker problem.…”

Section: Discussionsupporting

confidence: 86%

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Rendezvous search with markers that can be dropped at chosen times

Leone

Alpern

2018

Naval Research Logistics

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The Rendezvous search problem asks how two noncomunnicating players, who move at unit‐speed after a random placement in the search region (in this article, the line), can minimize their expected meeting time. Baston and Gal () solved a version where each player leaves a marker at his starting point, for example parachutes left after jumping into the search region. Here we consider that one or both players have markers which they can drop at chosen times. When the players are placed facing random directions at a distance D on the line the optimal expected meeting times R are known to be as follows: With no markers, R = 13D/8; with one each dropped at the start, R = 3D/2. Here we show that when only one player has a marker, but it can be dropped at any time, we still have R = 3D/2, obtained by dropping the marker at time D/4. Having both players drop markers at chosen times does not further reduce R. We adopt a new algorithmic approach which first fixes the dropping times and then reduces the resulting problem to a finite one. We also consider evanescent markers, which are detectable for a specified time T after being dropped, modeling pheromone scent markers used by some species in mate search or stain dropped by sailors. From a less theoretical and more practical point of view, we can see our problem as that faced by two hikers who get separated when they are walking not too far from a coast. A reasonable Rendezvous strategy is for each of them to head in the general direction of the coastline. On reaching the sea, they can calculate (based on their speed and time taken to reach to coast) the maximum distance along the coastline where the other one arrives. Then they can use our solution, taking that distance as our parameter D. Of course if it turns out that they reached the sea at points closer than D, their Rendezvous time will only be shorter. So our solution can be interpreted as a worst case expected meeting time. The marker might be a note scribbled on the sand, or a pile of rocks. Perhaps before getting separated they would have decided which roles (I or II) each would take up, being careful and cautious hikers. So in particular the hiker taking the role of the marker placer would put down a marker of some sort when he had walked along the coast one quarter the maximum distance to his partner. If the other finds it, he would know for sure the direction of the hiker who dropped it. Another thing to take away from this article is our result that says “two markers are not better than one.” This observation has some significance in the mate search context, where males and females use pheromone deposits to help find each other. In most species, it is only the females who can make such deposits, and the males can detect it. Giving both species the depositing facility would be more costly in terms of energy and, given our negative result, might not significantly reduce Rendezvous times. So in a speculative sense, our result has some explanatory value in this context.

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({\overset{true‾}{f}}_{3}, {\overset{true‾}{g}}_{3})

solution found in Theorem for the two marker problem.…”

Section: Discussionsupporting

confidence: 86%

“…A final comment is that our Rendezvousers use deterministic strategies, compared to earlier models ranging from the Brownian walker to the straight line walker in Mizumoto et al (b).…”

Section: Discussionmentioning

confidence: 93%

Rendezvous search with markers that can be dropped at chosen times

Leone

Alpern

2018

Naval Research Logistics

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“…Under the reunion search conditions, the results depended on the length of search time ( Fig. 3E, 3F), which had been predicted in the previous theoretical study (26). The sexually dimorphic movement achieved higher efficiency than the sexually monomorphic combinations when the search time was longer than ca.…”

Section: Assessment Of Searching Efficiency Of Random Walks By Termitessupporting

confidence: 78%

“…First, before pair-formation, individuals have no information to locate their potential partners, and they engage actively in random search with relatively straight motions (i.e., higher ρ values; Table 1). This should be adaptive, compared to their alternative movements, because the optimal strategy is moving straight without directional changes when targets are destructive (i.e., disappear after mating) and randomly distributed (3,15,26). Second, when a mated pair gets separated after pair-formation, the termites generally increase their turning rate and show remarkable sexually dimorphic movements: females pause frequently and males move actively (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…To conclude, biological details are essential when we evaluate the random search strategies of animals. Types of targets (9,26,51) and searching conditions (8) strongly affect the search efficiency and the resulting fitness. Comparative experiments across conditions as well as across species will offer an ideal opportunity to understand how animals search for uncertain targets in complex environments.…”

Section: Discussionmentioning

confidence: 99%

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Adaptive switch to sexually dimorphic movements by partner-seeking termites

Mizumoto

Dobata

2018

Preprint

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When searching for targets whose location is not known, animals should benefit by adopting movement patterns that promote random encounters. During mate search, theory predicts that the optimal search pattern depends on the expected distance to potential partners. A key question is whether actual males and females update their mate search patterns to increase encounter probability when conditions change. Here we show that two termite species, Reticulitermes speratus and Coptotermes formosanus, adaptively alternate between sexually monomorphic and dimorphic movements during mate search. After leaving their nests in a synchronized manner, termites begin to search for a mate. The resulting pairs perform tandem runs toward potential nest sites. We found that both sexes moved faster and in straight lines before finding partners, which is known to improve encounter rates when targets have completely unpredictable positions. In stark contrast, when pairs were accidentally separated during tandem running, they showed distinct sexually dimorphic movements, where females paused for long periods while males paused only briefly and moved actively. Data-based simulations demonstrated that such sexually dimorphic movements are advantageous when a mate is located nearby but its exact location is unknown. These results emphasize the importance of biological details to evaluate the efficiency of random search in animals. By extending the concept of mutual search beyond the context of mating, the dimorphic movements between partners represent a remarkable convergence between termites and other animals including humans. Significance StatementHow should females and males move to search for partners whose exact location is unknown? Theory predicts that the answer depends on what they know about where targets can be found, indicating that the question doesn't make sense until the searching context is clarified. We demonstrated that termites adaptively switch their search All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/340919 doi: bioRxiv preprint first posted online Jun. 8, 2018; 2 modes depending on the potential distance to their partners. When the location of potential mates was completely unpredictable, both sexes moved in straight lines to explore widely. In contrast, when the stray partner was at least nearby, males moved while females paused. Simulations confirmed that these movements increase the rate of successful encounters. The context-dependent switch of search modes is a key to enhance random encounters in animals. IntroductionMoving for survival and reproduction is nearly a defining characteristic of animals (1, 2). Their movement patterns to find targets depend on the availability of sensory information and/or memories about targets (3, 4). When searching for targets with little or no locational information, animal...

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Intrapopulation genetic variation in the level and rhythm of daily activity in Drosophila immigrans

Ueno

Takahashi

2020

Ecology and Evolution

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Individuals within a population vary in many traits, including both continuous and discontinuous characteristics such as sex, color, size, morphology, behavior, and personality. Studies on intraspecific genetic variation had focused on two areas fundamental to evolutionary ecology: the evolutionary processes generating genetic variation and the ecological consequences of the evolution of genetic variation in a species/population (Bolnick et al., 2011; Forsman, 2008). For example, population genetics revealed that intraspecific genetic variation is maintained in populations through balancing selection or a migration-selection balance (Mallet & Barton, 1989; Slatkin, 1973). Genetic variations are then suggested to enhance speciation and adaptive radiation over an evolutionary time scale (Mallet & Barton, 1989; Slatkin, 1973). On the other hand, ecological consequences of the genetic variation are getting

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Optimizing mating encounters by sexually dimorphic movements

Cited by 22 publications

References 38 publications

Rendezvous search with markers that can be dropped at chosen times

Rendezvous search with markers that can be dropped at chosen times

Adaptive switch to sexually dimorphic movements by partner-seeking termites

Intrapopulation genetic variation in the level and rhythm of daily activity in Drosophila immigrans

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